Input: cyapa - remove redundant assignment to 'pwr_cmd'

The variable pwr_cmd is being assigned to cyapa->suspend_power_mode
twice, once during the declaration and once after taking an
interruptible mutex lock.  Remove the redundant first assignment
since the value is never read and it is outside the mutex lock.

Cleans up clang warning:
drivers/input/mouse/cyapa.c:743:5: warning: Value stored to 'pwr_cmd'
during its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>