defconfig: gen3auto: Set CONFIG_BLK_DEV_LOOP_MIN_COUNT to 16 for vts test

Set CONFIG_BLK_DEV_LOOP_MIN_COUNT=16 that pre-create loop block
devices at init time for vts_kernel_loopconfig_test.

Change-Id: I136c0f620913d2ce8ddbb0ccbd8bc0b05f72a3ad
Signed-off-by: Vinay Sudra <vsudra@codeaurora.org>