atmel_nand: Remove undef during SPL_BUILD

We cannot disable features in SPL in this manner, remove the undef here.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/mtd/nand/raw/atmel_nand.c b/drivers/mtd/nand/raw/atmel_nand.c
index 9fbb0b5..b7e473c 100644
--- a/drivers/mtd/nand/raw/atmel_nand.c
+++ b/drivers/mtd/nand/raw/atmel_nand.c
@@ -38,10 +38,6 @@
 
 #ifdef CONFIG_ATMEL_NAND_HW_PMECC
 
-#ifdef CONFIG_SPL_BUILD
-#undef CONFIG_SYS_NAND_ONFI_DETECTION
-#endif
-
 struct atmel_nand_host {
 	struct pmecc_regs __iomem *pmecc;
 	struct pmecc_errloc_regs __iomem *pmerrloc;