drivers: modem: ublox-sara-r4: allocate in modem_cmd_handler with K_NO_WAIT
drivers: modem: ublox-sara-r4: allocate in modem_cmd_handler with K_NO_WAIT

All net_bufs allocated to modem_cmd_handler's data->rx_buf are consumed
synchronously in ublox-sara-r4.c in the same thread. This means that
allocating them with timeout makes no sense, because timeout
will *always* be hit when there are no more buffers in net_buf_pool.

Get rid of the unnecessary timeout, as it doesn't help and just slows
down processing of incoming data, increasing possibility of data
overrun.

Signed-off-by: Marcin Niestroj <63506c06cfbc47ace147db1702f6e751f5ac2132@grinn-global.com>

zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,nashif/zephyr,galak/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr