common/octeontx2: add IO handling APIs

common/octeontx2: add IO handling APIs

Various octeontx2 drivers use IO handling API, added octeontx2
specific IO handling routines in the common code.

Since some of those implementations are based on arm64 instructions
added the stub to compile the code on non arm64 ISA.
The non arm64 ISA stub is possible due to the fact that
it is an integrated controller i.e runs only on Marvell HW.

Signed-off-by: Jerin Jacob <jerinj@marvell.com>
Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>