get.sh: allow force-pull via -F instead of -f

use of ./mk -F behaves the same as -f before the
previous commit.

this can be useful, during development when we want
to update revisions.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/get.sh

@@ -232,7 +232,8 @@ try_git()
 		x_ mv "$tmpgitcache" "$gitdest"
 	fi
 
-	if git -C "$gitdest" whatchanged "$7" 1>/dev/null 2>/dev/null; then
+	if git -C "$gitdest" whatchanged "$7" 1>/dev/null 2>/dev/null && \
+	    [ "$forcepull" != "y" ]; then
 		# don't try to pull the latest changes if the given target
 		# revision already exists locally. this saves a lot of time
 		# during release builds, and reduces the chance that we will