powerpc/uaccess: correct check for CONFIG_PPC_E500 in mask_user_address()

powerpc/uaccess: correct check for CONFIG_PPC_E500 in mask_user_address()

mask_user_address() incorrectly checks for CONFIG_E500 instead of
CONFIG_PPC_E500, causing mask_user_address_isel() to not be used on
E500 hardware. Fix the check to use the correct name.

Fixes: 861574d51bbd ("powerpc/uaccess: Implement masked user access")
Cc: stable@vger.kernel.org # 7.0+
Signed-off-by: Ethan Nelson-Moore <enelsonmoore@gmail.com>
Fixes: 861574d51bbd ("powerpc/uaccess: Implement masked user access")
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260615233729.29386-1-enelsonmoore@gmail.com