[][mtd: nand: spi: Fix build error]

[Description]
Fix build error

[Release-log]
N/A

Change-Id: I7b64faade226ff0a3d94cc9821d61a927b135205
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/5509059
1 file changed