test_mkfs_extraopts test case fails on ab with error caused
by using -K --mixed options:
output: extent-tree.c:2696: btrfs_reserve_extent: BUG_ON `ret` triggered, value -28
For this test case it's not important to use particular options,
so changing options to anything less influential is OK.
Changed extra options for mkfs.btrfs to '--quiet' to fix the failure.
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
