xen/arm64: Remove READ/WRITE_SYSREG32 helper macros

xen/arm64: Remove READ/WRITE_SYSREG32 helper macros

AArch64 system registers are 64bit whereas AArch32 ones
are 32bit or 64bit. MSR/MRS are expecting 64bit values thus
we should get rid of helpers READ/WRITE_SYSREG32
in favour of using READ/WRITE_SYSREG.

The last place in code making use of READ/WRITE_SYSREG32
on arm64 is in TVM_REG macro defining functions vreg_emulate_<register>.
Implement a macro WRITE_SYSREG_SZ which expands as follows:
-on arm64: WRITE_SYSREG
-on arm32: WRITE_SYSREG{32/64}

As there are no other places in the code using these helpers
on arm64 - remove them.

Signed-off-by: Michal Orzel <michal.orzel@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Acked-by: Stefano Stabellini <sstabellini@kernel.org>