ArmPkg: Extend number of parameter registers in SMC call

The Realm Service Interface (RSI) commands use registers between
X1-X10 as parameters and between X0-X8 as return values for SMC
calls.

According to the SMCCC Section 2.6 SMC32/HVC32 argument passing
  When an SMC32/HVC32 call is made from AArch32:
   - Arguments are passed in registers R1-R7.
   - Results are returned in R0-R7.
  When an SMC32/HVC32 call is made from AArch64:
   - Arguments are passed in registers W1-W7.
   - Results are returned in W0-W7.

According to SMCCC Section 2.7 SMC64/HVC64 argument passing
  When an SMC64/HVC64 call is made from AArch64:
   - Arguments are passed in registers X1-X17.
   - Results are returned in X0-X17.

This means SMC calls can take up to 7/17 arguments and return up
to 7/17 return values.

However, for the current use-case(s):
  - SMC32/HVC32 calls made from AArch32/AArch64 require up to 7
    arguments and 4 return values.
  - SMC64/HVC64 calls made from AArch64 require up to 10 arguments
    and 9 return values.

Therefore, for SMC32/HVC32 calls made from AArch32/AArch64 there is
no update required. However, for AMC64/HVC64 calls made from AArch64,
extend the ArmCallSmc () to use registers X1-X11 as parameters and
return values for SMC call.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>