feat(fpu): add helper routines to read, write, compare FPU registers

Add helper routines to read, write, write_rand and compare FPU state
and FPU control/status registers.

These helper routines can be called by testcases running in NS-EL2,
R-EL1, S-EL1 payload. The caller has to pass memory to read/write FPU
registers.

Signed-off-by: Arunachalam Ganapathy <arunachalam.ganapathy@arm.com>
Change-Id: I10ae5487c9f58e46434c1bd5b42fd458ec755045
7 files changed