tests: x86/pagetables: limit permission test under demand paging
tests: x86/pagetables: limit permission test under demand paging

When demand paging is enabled and not all generic sections are
in physical memory at boot, only tests the permission up to the end
of the pinned section.

Signed-off-by: Daniel Leung <d94e04d205b5962d7873a139ef298b03c1717f72@intel.com>

finikorg/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr