docsrc: fix crc32hash type

Fix differing signedness warning:

Documentation/pcmcia/crc32hash.c:29: warning: pointer targets in passing argument 1 of 'crc32' differ in signedness

Signed-off-by: Randy Dunlap <[e-mail]>
Acked-by: Dominik Brodowski <[e-mail]>
Cc: Sam Ravnborg <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/pcmcia/crc32hash.c

···
 		printf("no string passed as argument\n");
 		return -1;
 	}
-	result = crc32(argv[1], strlen(argv[1]));
+	result = crc32((unsigned char const *)argv[1], strlen(argv[1]));
 	printf("0x%x\n", result);
 	return 0;
 }