serial: mrst_max3110: make buffer larger

This is used to store the spi_device ->modalias so they have to be the same
size.  SPI_NAME_SIZE is 32.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>