nand: fix nand read.option parsing

"nand read.part addr off size" would be treated as "nand read.raw addr off 1"
It now fails as intended stating "Unknown nand command suffix '.part'"
Signed-off-by: NHarvey Chapman <hchapman@3gfp.com>

common/cmd_nand.c

@@ -608,7 +608,7 @@ static int do_nand(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 		size_t rwsize;
 		ulong pagecount = 1;
 		int read;
-		int raw;
+		int raw = 0;
 
 		if (argc < 4)
 			goto usage;