BACKPORT: arm64: use ENDPIPROC() to annotate position independent assembler routines

For more control over which functions are called with the MMU off or
with the UEFI 1:1 mapping active, annotate some assembler routines as
position independent. This is done by introducing ENDPIPROC(), which
replaces the ENDPROC() declaration of those routines.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Bug: 31432001
Change-Id: I757ad5a4e90100c8b56eff97a877e59463705db1
(cherry picked from commit 20791846)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>