x86: remove suprious ifdefs from pageattr.c

The .rodata section really should just be read only; the config option
is there to make breaking up the 2Mb page an option (so people whos machines
give more performance for the 2Mb case can opt to do so).
But when the page gets split anyway, this is no longer an issue, so
clean up the code and remove the ifdefs

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>