staging: crystalhd: Fix typo in crystalhd_hw.c

Correct spelling "interal" to "internal" in
drivers/staging/crystalhd/crystalhd_hw.c

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>