msm_serial_hs: Fix spinlock recursion in handling CTS

msm_hs_handle_delta_cts tries to acquire port->lock already acquired
by the callee function msm_hs_isr. Change function name to follow
"_locked" convention.

Signed-off-by: Mayank Rana <mrana@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>