powerpc/64s: Rewrite __real_pte() and __rpte_to_hidx() as static inline

powerpc/64s: Rewrite __real_pte() and __rpte_to_hidx() as static inline

Rewrite __real_pte() and __rpte_to_hidx() as static inline in order to
avoid following warnings/errors when building with 4k page size:

	  CC      arch/powerpc/mm/book3s64/hash_tlb.o
	arch/powerpc/mm/book3s64/hash_tlb.c: In function 'hpte_need_flush':
	arch/powerpc/mm/book3s64/hash_tlb.c:49:16: error: variable 'offset' set but not used [-Werror=unused-but-set-variable]
	   49 |         int i, offset;
	      |                ^~~~~~

	  CC      arch/powerpc/mm/book3s64/hash_native.o
	arch/powerpc/mm/book3s64/hash_native.c: In function 'native_flush_hash_range':
	arch/powerpc/mm/book3s64/hash_native.c:782:29: error: variable 'index' set but not used [-Werror=unused-but-set-variable]
	  782 |         unsigned long hash, index, hidx, shift, slot;
	      |                             ^~~~~

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501081741.AYFwybsq-lkp@intel.com/
Fixes: ff31e105464d ("powerpc/mm/hash64: Store the slot information at the right offset for hugetlb")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/e0d340a5b7bd478ecbf245d826e6ab2778b74e06.1736706263.git.christophe.leroy@csgroup.eu