mtd: cfi_probe: use P_ID_* definitions instead of hardcoded values

Use P_ID_* definitions already in include/linux/mtd/cfi.h instead of the
hardcoded values. Make the code more readable.

Signed-off-by: Guillaume LECERF <glecerf@gmail.com>
Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/chips/gen_probe.c b/drivers/mtd/chips/gen_probe.c
index fcc1bc0..1d56887 100644
--- a/drivers/mtd/chips/gen_probe.c
+++ b/drivers/mtd/chips/gen_probe.c
@@ -241,17 +241,17 @@
 		/* We need these for the !CONFIG_MODULES case,
 		   because symbol_get() doesn't work there */
 #ifdef CONFIG_MTD_CFI_INTELEXT
-	case 0x0001:
-	case 0x0003:
-	case 0x0200:
+	case P_ID_INTEL_EXT:
+	case P_ID_INTEL_STD:
+	case P_ID_INTEL_PERFORMANCE:
 		return cfi_cmdset_0001(map, primary);
 #endif
 #ifdef CONFIG_MTD_CFI_AMDSTD
-	case 0x0002:
+	case P_ID_AMD_STD:
 		return cfi_cmdset_0002(map, primary);
 #endif
 #ifdef CONFIG_MTD_CFI_STAA
-        case 0x0020:
+        case P_ID_ST_ADV:
 		return cfi_cmdset_0020(map, primary);
 #endif
 	default: