secimage: Use libz's crc32 function

This is to trick libreboot into not deleting misc.c when checking
out coreboot.

Change-Id: I8f0bb5cb3eb5681f99c616ae03de126efab852a9
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/11134
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/broadcom/secimage/secimage.h

@@ -39,7 +39,6 @@ int DataRead(char *filename, uint8_t *buf, int *length);
 int AppendHMACSignature(uint8_t *data, uint32_t length, char *filename,
 			uint32_t offset);
 int ReadBinaryFile(char *fname, uint8_t *buf, int maxlen);
-uint32_t calc_crc32(uint32_t initval, uint8_t *charArr, uint32_t arraySize);
 void FillHeaderFromConfigFile(char *h, char *ConfigFileName);
 
 #endif /* _SECIMAGE_H_ */