scripts: tizen: sd_fusing_rpi3: update the rpi3 script

scripts: tizen: sd_fusing_rpi3: update the rpi3 script

To prevent wrong operation, check the result whether format is succeed
or not. If it's failed, exit this script.
And if there is already "mnt_tmp" directory, remove it to clear the
previous status.

It's changed the location to remove a partition table with dd command
with count is changed  from 16 to 32.
Because  it seems that partition table doesn't clear.

Change-Id: Id3eb739d5add8784d0f41eca8a7e4360a8a0dbfd
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>