err.h: add ERR_PTR_PCPU(), PTR_ERR_PCPU() and IS_ERR_PCPU() macros

Add ERR_PTR_PCPU(), PTR_ERR_PCPU() and IS_ERR_PCPU() macros that operate
on pointers in the percpu address space.

These macros remove the need for (__force void *) function argument casts
(to avoid sparse -Wcast-from-as warnings).

The patch will also avoid future build errors due to pointer address space
mismatch with enabled strict percpu address space checks.

Link: https://lkml.kernel.org/r/20240818210235.33481-1-ubizjak@gmail.com


Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>