envsetup.sh: partly fix syswrite

The grep doesn't work because "Reboot" is capitalized in the
enable-verity output. Now, syswrite gets farther, but fails before the
final remount.

    $ syswrite
    adbd is already running as root
    Successfully disabled verity
    Enabled overlayfs
    rebooting
    restarting adbd as root
    error: closed

Test: ran syswrite on freshly flashed device
Change-Id: I26aaa6278d76dcab56fd4bde3d70ac7841ae2a3b

envsetup.sh

@@ -1069,7 +1069,7 @@ function qpid() {
 # Easy way to make system.img/etc writable
 function syswrite() {
   adb wait-for-device && adb root || return 1
-  if [[ $(adb disable-verity | grep "reboot") ]]; then
+  if [[ $(adb disable-verity | grep -i "reboot") ]]; then
       echo "rebooting"
       adb reboot && adb wait-for-device && adb root || return 1
   fi