Drop prototype guarding for romcc

Commit "romcc: Don't fail on function prototypes" (11a7db3b) [1]
made romcc not choke on function prototypes anymore. This
allows us to get rid of a lot of ifdefs guarding __ROMCC__ .

[1] http://review.coreboot.org/2424

Change-Id: Ib1be3b294e5b49f5101f2e02ee1473809109c8ac
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/3216
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/include/ip_checksum.h

@@ -1,8 +1,5 @@
 #ifndef IP_CHECKSUM_H
 #define IP_CHECKSUM_H
-
-#ifndef __ROMCC__
 unsigned long compute_ip_checksum(void *addr, unsigned long length);
 unsigned long add_ip_checksums(unsigned long offset, unsigned long sum, unsigned long new);
-#endif
 #endif /* IP_CHECKSUM_H */