MIPS: Alchemy: add helpers to access static memory ctrl registers.

This patch changes the static memory controller registers to offsets
from base, prefixes them with AU1000_ to avoid silent failures due to
changed addresses and introduces helpers to access them.

No functional changes, comparing assembly of a few select functions shows
no differences.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/7463/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/alchemy/devboards/db1300.c b/arch/mips/alchemy/devboards/db1300.c
index 1aed6be..c80e5b9 100644
--- a/arch/mips/alchemy/devboards/db1300.c
+++ b/arch/mips/alchemy/devboards/db1300.c
@@ -169,7 +169,7 @@
 
 static int au1300_nand_device_ready(struct mtd_info *mtd)
 {
-	return __raw_readl((void __iomem *)MEM_STSTAT) & 1;
+	return alchemy_rdsmem(AU1000_MEM_STSTAT) & 1;
 }
 
 static struct mtd_partition db1300_nand_parts[] = {