mtd: rawnand: sunxi: Add an U suffix to NFC_PAGE_OP definition

Fixes the "warning: large integer implicitly truncated to unsigned type
[-Woverflow]" warning when compiled for x86.

This is needed in order to allow compiling this driver when
COMPILE_TEST=y.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/sunxi_nand.c

@@ -127,7 +127,7 @@
 #define NFC_CMD_TYPE_MSK	GENMASK(31, 30)
 #define NFC_NORMAL_OP		(0 << 30)
 #define NFC_ECC_OP		(1 << 30)
-#define NFC_PAGE_OP		(2 << 30)
+#define NFC_PAGE_OP		(2U << 30)
 
 /* define bit use in NFC_RCMD_SET */
 #define NFC_READ_CMD_MSK	GENMASK(7, 0)