selftests/mm: rename pkey register macro

selftests/mm: rename pkey register macro

PKEY_ALLOW_ALL is meant to represent the pkey register value that allows
all accesses (enables all pkeys).  However its current naming suggests
that the value applies to *one* key only (like PKEY_DISABLE_ACCESS for
instance).

Rename PKEY_ALLOW_ALL to PKEY_REG_ALLOW_ALL to avoid such
misunderstanding.  This is consistent with the PKEY_REG_ALLOW_NONE macro
introduced by commit 6e182dc9f268 ("selftests/mm: Use generic pkey
register manipulation").

Link: https://lkml.kernel.org/r/20241209095019.1732120-13-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Keith Lucas <keith.lucas@oracle.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>