arm64: efi-entry.S: avoid open-coded adr_l

Some places in the kernel open-code sequences using ADRP for a symbol
another instruction using a :lo12: relocation for that same symbol.
These sequences are easy to get wrong, and more painful to read than is
necessary. For these reasons, it is preferable to use the
{adr,ldr,str}_l macros for these cases.

This patch makes use of these in efi-entry.S, removing open-coded
sequences using adrp.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>