powerpc/configs: Drop no longer needed CONFIG_LIBCRC32C

Since commit 300ae149 ("netfilter: select LIBCRC32C together with
SCTP conntrack") we no longer need to set CONFIG_LIBCRC32C in our
defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/pmac32_defconfig

@@ -300,7 +300,6 @@ CONFIG_NFSD_V4=y
 CONFIG_NLS_CODEPAGE_437=m
 CONFIG_NLS_ISO8859_1=m
 CONFIG_CRC_T10DIF=y
-CONFIG_LIBCRC32C=m
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_KERNEL=y
 CONFIG_DETECT_HUNG_TASK=y