s390: Remove remaining _PAGE_* macros

s390: Remove remaining _PAGE_* macros

The introduction of vdso/page.h made the definition of _PAGE_SHIFT,
_PAGE_SIZE, _PAGE_MASK redundant.

Refactor the code to remove the macros.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241014151340.1639555-4-vincenzo.frascino@arm.com
Closes: https://lore.kernel.org/oe-kbuild-all/202410112106.mvc2U2p0-lkp@intel.com/