Bluetooth: btnxpuart: Add handling for boot-signature timeout errors

This handles the timeout error codes sent by the chip as part of the
bootloader signatures during firmware download process.

When the bootloader does not receive a response packet from the host
within a specific time, it adds an error code to the bootloader
signature while requesting for the FW chunk from the same offset.

The host is expected to clear this error code with a NAK, and reply to
only those bootloader signatures which have error code 0.

However, the driver was ignoring this error code and replying with the
firmware chunks instead, which is apparently ignored by the chip and the
chip resends the same bootloader signature with the error code again. This
happens in a loop until the error code self clears and firmware download
proceeds ahead, adding a couple of milliseconds to the total firmware
download time.

Commit 689ca16e was an initial implementation which simply printed
the following line during driver debug:
- FW Download received err 0x04 from chip

This commit adds the expected handling to the error codes.

This error handling is valid for data_req bootloader signatures for V3
and future bootloader versions.

Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@nxp.com>
Fixes: 689ca16e ("Bluetooth: NXP: Add protocol support for NXP Bluetooth chipsets")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>