powerpc/64: Replace -mcpu=e500mc64 by -mcpu=e5500

E500MC64 is a processor pre-dating E5500 that has never been
commercialised. Use -mcpu=e5500 for E5500 core.

More details at https://gcc.gnu.org/PR108149Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/fa71ed20d22c156225436374f0ab847daac893bc.1671475543.git.christophe.leroy@csgroup.eu

arch/powerpc/platforms/Kconfig.cputype

@@ -257,7 +257,7 @@ config TARGET_CPU
 	default "power8" if POWER8_CPU
 	default "power9" if POWER9_CPU
 	default "power10" if POWER10_CPU
-	default "e500mc64" if E5500_CPU
+	default "e5500" if E5500_CPU
 	default "e6500" if E6500_CPU
 	default "power4" if POWERPC64_CPU && !CPU_LITTLE_ENDIAN
 	default "power8" if POWERPC64_CPU && CPU_LITTLE_ENDIAN