mtd: nuc900_nand: NULL dereference in nuc900_nand_enable()

commit c69dbbf3 upstream.

Instead of writing to "nand->reg + REG_FMICSR" we write to "REG_FMICSR"
which is NULL and not a valid register.

Fixes: 8bff82cb ('mtd: add nand support for w90p910 (v2)')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mtd/nand/nuc900_nand.c

@@ -250,7 +250,7 @@ static void nuc900_nand_enable(struct nuc900_nand *nand)
 	val = __raw_readl(nand->reg + REG_FMICSR);
 
 	if (!(val & NAND_EN))
-		__raw_writel(val | NAND_EN, REG_FMICSR);
+		__raw_writel(val | NAND_EN, nand->reg + REG_FMICSR);
 
 	val = __raw_readl(nand->reg + REG_SMCSR);