ANDROID: ipi: Add function to return nr_ipi and ipi_desc

For implementation of IPI stats, nr_ipi and ipi_desc are useful.
This information helps in getting per cpu IPI count and total
IPI count from vendor module.

Presently, there are no helper functions to get nr_ipi and
ipi_desc on vendor side. And if we do with a new exported symbol
that does kallsyms_lookup_name on each static variable takes
more than 80ms during boot up or for the first access of each
static variable is an overhead.

So lets add helper functions to return nr_ipi and ipi_desc
value to get things done in an efficient way.

Bug: 177393446
Change-Id: I698dbbb0301d4f1529ef7484f25fe7540378008c
Signed-off-by: Prateek Sood <prsood@codeaurora.org>
Signed-off-by: Mukesh Ojha <mojha@codeaurora.org>