arm64: kernel: do not need to reset UAO on exception entry

arm64: kernel: do not need to reset UAO on exception entry

Commit e19a6ee2460b ("arm64: kernel: Save and restore UAO and
addr_limit on exception entry") states that exception handler inherits
the original PSTATE.UAO value, so UAO needes to be reset
explicitly. However, ARM 8.2 Extension documentation says:

PSTATE.UAO is copied to SPSR_ELx.UAO and is then set to 0 on an
exception taken from AArch64 to AArch64

so hardware already does the right thing.

Signed-off-by: Vladimir Murzin <[email protected]>
Acked-by: James Morse <[email protected]>
Signed-off-by: Will Deacon <[email protected]>