arm_mpam: Introduce flexible CLOSID/RMID translation

Currently, the MPAM driver uses the resctrl CLOSID directly as the
MPAM Partition Identifier (PARTID; possibly modified to give
different PARTIDs to code and data when Code/Data Partitioning /
CDP is enabled), and uses the resctrl RMID directly as the MPAM
Performance Monitoring Group identifier (PMG).

In preparation for using the MPAM PARTID Narrowing feature to allow
more resctrl monitoring groups to be provided than the number of
PMG values supported by the hardware, a more flexible remapping
scheme is needed.

Factor out ID translation operations in the MPAM resctrl glue code
into a couple of self-contained helpers, and call them as
appropriate.

The translation scheme has a single parameter, partid_per_closid,
which is currently hard-wired to 1.

As a result, this patch should have no effect on functionality.

Logic to determine / control the mapping parameters can be
introduced later.

The ID transformation may be visualised as follows:

without CDP:
  +---------------------------------------------------+-----------+
  |                       CLOSID                      |    RMID   |
  +---------------------------------------------------+-------+---+
  |                           PARTID                  :       |PMG|
  +-----------------------------------------------------------+---+

and with CDP, where the "CDP" field is 0 for the data sub-
partition and 1 for the code sub-partition:
  +-----------------------------------------------+---+-----------+
  |                     CLOSID                    |CDP|    RMID   |
  +-----------------------------------------------+---+-------+---+
  |                           PARTID                  :       |PMG|
  +-----------------------------------------------------------+---+

where each box represents a non-negative integer spanning some
fixed range starting from zero, and horizontal concatenation
denotes multiplying the value denoted by the left-hand box by the
span of the right-hand box, and adding the result to the value
denoted by the right-hand box; thus, most-significant fields are on
the left.

(Except for the span of each field not necessarily being a power of
two, this is conceptually identical to concatenation and cutting of
bitfields.)

The dotted segment indicates the least significant part of PARTID,
which spans partid_per_closid PARTIDs and discriminates monitoring
groups that use the same MPAM PMG value.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>

---

Changes since RFCv1:

 * [bugfix] Add CDP index properly in mpam_resctrl_partid_range().

   (Also reported by Shaopeng Tan.)

 * [relaxation] Remove requirement that mpam_pmg_max + 1 is a power
   of two.

   (This constraint is redundant, due to the use of multiply/add
   transformations of MPAM IDs in place of shift/OR.)