IA64: includecheck fix: ia64, pgtable.h

fix the following 'make includecheck' warning:

  arch/ia64/include/asm/pgtable.h: asm/processor.h is included more than once.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Acked-by: Fenghua Yu <fenghua.yu@intel.com>