powerpc/nohash: Remove pte_same()

arch/powerpc/include/asm/nohash/{32/64}/pgtable.h has

	#define __HAVE_ARCH_PTE_SAME
	#define pte_same(A,B)      ((pte_val(A) ^ pte_val(B)) == 0)

include/linux/pgtable.h has

	#ifndef __HAVE_ARCH_PTE_SAME
	static inline int pte_same(pte_t pte_a, pte_t pte_b)
	{
		return pte_val(pte_a) == pte_val(pte_b);
	}
	#endif

Remove the powerpc version which is similar to the generic one.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/83c97bd58a3596ef1b0ff28b1e41fd492d005520.1643616989.git.christophe.leroy@csgroup.eu