Drop support for RAWFS partition

We are not using it, and it triggers compiler warnings.

hmx_upgrade_nvram.c: In function 'HMX_NVRAM_SetField':
hmx_upgrade_nvram.c:896:7: error:
implicit declaration of function 'DRV_NANDFLASH_GetNvramHandle'
hmx_upgrade_nvram.c:901:7: error:
implicit declaration of function 'DRV_FLASH_Write'

Change-Id: Ib2d84e02c9c9c72ff20bfdef880f2331af3894d9
diff --git a/libupgrade/hmx_upgrade_nvram.c b/libupgrade/hmx_upgrade_nvram.c
index caa4233..2fe67b2 100644
--- a/libupgrade/hmx_upgrade_nvram.c
+++ b/libupgrade/hmx_upgrade_nvram.c
@@ -894,19 +894,7 @@
 
   switch (partition) {
     case HMX_NVRAM_PARTITION_W_RAWFS :
-      errCode = DRV_NANDFLASH_GetNvramHandle(&nvramHandle);
-      if (errCode != DRV_OK) {
-        return errCode;
-      }
-
-      errCode = DRV_FLASH_Write(s_nvram_offset[HMX_NVRAM_PARTITION_W_RAWFS] +
-                                offset, data, nDataSize);
-      if (errCode != DRV_OK) {
-        DEBUG_ERR("[HMX_NVRAM_SetField] field(%d)-%s error(%08X) : "
-                  "HMX_NVRAM_Write\n", field, szFileName, errCode);
-        return errCode;
-      }
-      break;
+      return DRV_ERR_INVALID_PARAMETER;
     case HMX_NVRAM_PARTITION_RO :
     case HMX_NVRAM_PARTITION_RW :
       if (defaultSize == 0) {