[MTD] [NAND] Fix compiler warning in Alauda driver

drivers/mtd/nand/alauda.c: In function 'alauda_bounce_read':
drivers/mtd/nand/alauda.c:412: warning: comparison of distinct pointer types lacks a cast

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>