Revert "SCSI: Enable SCSI_MQ_DEFAULT"

This reverts commit 16d7f29d46.  There
seem to be a lot of important fixes going into 4.15 for blk-mq, most
of which aren't tagged for stable, making it look a bit risky as a
default for 4.14.  I'll probably re-enable this for 4.15-rc.

debian/changelog

@@ -18,8 +18,6 @@ linux (4.14.2-1) UNRELEASED; urgency=medium
     - video: Disable USB_APPLEDISPLAY, BACKLIGHT_CLASS_DEVICE
   * apparmor: fix oops in audit_signal_cb hook (regression in 4.14)
   * leds: Enable LEDS_BRIGHTNESS_HW_CHANGED (Closes: #872862)
-  * SCSI: Enable SCSI_MQ_DEFAULT. This can be reverted using the kernel
-    parameter: scsi_mod.use_blk_mq=n
   * [rt] Add new signing subkey for Steven Rostedt
   * [rt] Update to 4.14.1-rt3
   * Set ABI to 1

debian/config/config

@@ -4204,7 +4204,6 @@ CONFIG_RTC_DRV_AB3100=m
 ##
 CONFIG_RAID_ATTRS=m
 CONFIG_SCSI=m
-CONFIG_SCSI_MQ_DEFAULT=y
 # CONFIG_SCSI_PROC_FS is not set
 CONFIG_BLK_DEV_SD=m
 CONFIG_CHR_DEV_ST=m