Revert wrong removal of nand_init and nand_deselect

The manual resolution in commit ec7023db wrongly removed functions
nand_init and nand_deselect from file drivers/mtd/nand/mxc_nand_spl.c.
Revert this removal.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
Acked-by: Stefano Babic <sbabic@denx.de>
diff --git a/drivers/mtd/nand/mxc_nand_spl.c b/drivers/mtd/nand/mxc_nand_spl.c
index f13d5fc..ba725e9 100644
--- a/drivers/mtd/nand/mxc_nand_spl.c
+++ b/drivers/mtd/nand/mxc_nand_spl.c
@@ -359,3 +359,6 @@
 	}
 }
 #endif
+
+void nand_init(void) {}
+void nand_deselect(void) {}