Blackfin: convert to generic checksum code

The Blackfin port only implemented an optimized version of the
csum_tcpudp_nofold function, so convert everything else to the new
generic code.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index ae6a60f..c0d4445 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -28,6 +28,9 @@
 	select HAVE_OPROFILE
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 
+config GENERIC_CSUM
+	def_bool y
+
 config GENERIC_BUG
 	def_bool y
 	depends on BUG