arm64: mm: get rid of kimage_vaddr global variable

arm64: mm: get rid of kimage_vaddr global variable

We store the address of _text in kimage_vaddr, but since commit
09e3c22a86f6889d ("arm64: Use a variable to store non-global mappings
decision"), we no longer reference this variable from modules so we no
longer need to export it.

In fact, we don't need it at all so let's just get rid of it.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20231129111555.3594833-46-ardb@google.com
Signed-off-by: Will Deacon <will@kernel.org>