arm64: Make ESR_ELx_xVC_IMM_MASK compatible with assembly

ESR_ELx_xVC_IMM_MASK is used as a mask for the immediate value for the
HVC/SMC instructions. The header file is included by assembly files (like
entry.S) and ESR_ELx_xVC_IMM_MASK is not conditioned on __ASSEMBLY__ being
undefined. Use the UL() macro for defining the constant's size, as that is
compatible with both C code and assembly, whereas the UL suffix only works
for C code.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220425114444.368693-2-alexandru.elisei@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>