Bluetooth: btnxpuart: Handle FW Download Abort scenario

Bluetooth: btnxpuart: Handle FW Download Abort scenario

This adds a new flag BTNXPUART_FW_DOWNLOAD_ABORT which handles the
situation where driver is removed while firmware download is in
progress.

logs:
modprobe btnxpuart
[65239.230431] Bluetooth: hci0: ChipID: 7601, Version: 0
[65239.236670] Bluetooth: hci0: Request Firmware: nxp/uartspi_n61x_v1.bin.se
rmmod btnxpuart
[65241.425300] Bluetooth: hci0: FW Download Aborted

Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Tested-by: Guillaume Legoupil <guillaume.legoupil@nxp.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>