Revert "hooks: add ti-u-boot to the / exception"

This reverts commit 0c575fbf6846a6a4ca40f06548ed3f3fa3fc4ec5.

Reason for revert: The ti-u-boot package has updated its install
to use /boot, so we can stop ignoring it.

Original change's description:
> hooks: add ti-u-boot to the / exception
> 
> BUG=b:150818446
> TEST=CQ passes
> 
> Change-Id: I1f3f0ee86d27c0cf878fd4ed1fed8cf360108360
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2088354
> Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
> Commit-Queue: Mike Frysinger <vapier@chromium.org>
> Tested-by: Mike Frysinger <vapier@chromium.org>

BUG=b:150818446

Change-Id: I66040cc8bec18e308af38eb06590b22dacc2705c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/2090123
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Alan Jones <alanjones@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
diff --git a/hooks/filesystem-sanity.py b/hooks/filesystem-sanity.py
index 26de940..0e0da32 100755
--- a/hooks/filesystem-sanity.py
+++ b/hooks/filesystem-sanity.py
@@ -76,8 +76,6 @@
     'dev-go/go-tools',
     # TODO(b/150694105): Delete this.
     'net-wireless/wpantund',
-    # TODO(b/150818446): Delete this.
-    'sys-boot/ti-u-boot',
 }
 
 # These SDK packages need cleanup.