Staging: btmtk_usb: Removal of Unnecessary white spaces

The patch fixes the following checkpatch.pl warning in btmtk_usb.c
WARNING: unnecessary whitespace before a quoted newline

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>