usb: storage: alauda: Remove set but unchecked variable

usb: storage: alauda: Remove set but unchecked variable

The return value of alauda_get_media_status() hasn't been checked
since the driver's inception back in 2005.  If nothing have gone
wrong/been detected until this point, it's probably safe to just
remove the variable.

Fixes the following W=1 kernel build warning(s):

 drivers/usb/storage/alauda.c: In function ‘alauda_check_media’:
 drivers/usb/storage/alauda.c:456:6: warning: variable ‘rc’ set but not used [-Wunused-but-set-variable]
 456 | int rc;
 | ^~

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Daniel Drake <dsd@gentoo.org>
Cc: usb-storage@lists.one-eyed-alien.net
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200703174148.2749969-20-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>