d855: use sdFAT for VFAT

Change-Id: I660c5b3008636a651a2812fe1739ff8a2ea845cb

rootdir/etc/fstab.g3

@@ -14,7 +14,7 @@
 /dev/block/platform/msm_sdcc.1/by-name/persist      /persist        ext4    nosuid,nodev,barrier=1,data=ordered,nodelalloc,nomblk_io_submit,errors=panic wait,notrim
 /dev/block/platform/msm_sdcc.1/by-name/boot         /boot           emmc    defaults                                                            recoveryonly
 /dev/block/platform/msm_sdcc.1/by-name/recovery     /recovery       emmc    defaults                                                            recoveryonly
-/dev/block/platform/msm_sdcc.1/by-name/modem        /firmware       vfat    ro,shortname=lower,uid=1000,gid=1026,dmask=227,fmask=337,context=u:object_r:firmware_file:s0 wait
+/dev/block/platform/msm_sdcc.1/by-name/modem        /firmware       sdfat   ro,uid=1000,gid=1026,dmask=227,fmask=337,context=u:object_r:firmware_file:s0 wait
 /dev/block/platform/msm_sdcc.1/by-name/pad          /misc           emmc    defaults                                                            defaults
 
 /dev/block/platform/msm_sdcc.1/by-name/sns          /sns            ext4    nosuid,nodev,barrier=1,noatime,noauto_da_alloc,errors=continue      wait,notrim