parisc: Kconfig: cleanup Kernel page size default

"Kernel page size" still defaults to "4KB", for both 32 and 64 bit
processors, when tested with "make ARCH=parisc menuconfig".

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>