powerpc: Remove CONFIG_PPC_MMU_NOHASH_32

Since commit Fixes: 555904d0 ("powerpc/8xx: MM_SLICE is not needed anymore"),
CONFIG_PPC_MMU_NOHASH_32 has not been used.

Remove it.
Reported-by: Tom Rix <trix@redhat.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bf1e074f6fb213a1c4cc4964370bdce4b648d647.1622706812.git.christophe.leroy@csgroup.eu

arch/powerpc/platforms/Kconfig.cputype

@@ -424,10 +424,6 @@ config PPC_MMU_NOHASH
 	def_bool y
 	depends on !PPC_BOOK3S
 
-config PPC_MMU_NOHASH_32
-	def_bool y
-	depends on PPC_MMU_NOHASH && PPC32
-
 config PPC_BOOK3E_MMU
 	def_bool y
 	depends on FSL_BOOKE || PPC_BOOK3E