Staging: btmtk_usb: Fix line length exceeding 80 characters using min_t macro

This patch fixes the following checkpatch.pl warning in btmtk_usb.c:
WARNING: line over 80 characters in the file
by using kernel built_in min_t macro.

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Zach Brown <zab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>