arm64: hibernate: add __force attribute to gfp_t casting

arm64: hibernate: add __force attribute to gfp_t casting

Two new warnings are reported by sparse:

"sparse warnings: (new ones prefixed by >>)"
>> arch/arm64/kernel/hibernate.c:181:39: sparse: sparse: cast to
   restricted gfp_t
>> arch/arm64/kernel/hibernate.c:202:44: sparse: sparse: cast from
   restricted gfp_t

gfp_t has __bitwise type attribute and requires __force added to casting
in order to avoid these warnings.

Fixes: 50f53fb72181 ("arm64: trans_pgd: make trans_pgd_map_page generic")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Link: https://lore.kernel.org/r/20210201150306.54099-2-pasha.tatashin@soleen.com
Signed-off-by: Will Deacon <will@kernel.org>