linux-firmware: add firmware files for NXP BT chipsets

linux-firmware: add firmware files for NXP BT chipsets

These BT only firmware files are submitted for NXP chips.

88w8997-bt:
uartuart8997_bt_v4.bin version: 16.92.21.p81
helper_uart_3000000.bin version: 16.92.21.p81

88w8987-bt:
uartuart8987_bt.bin version: 16.92.21.p76.5

88w9098-bt:
uartuart9098_bt_v1.bin version: 17.92.1.p136.24

iw416-bt:
uartiw416_bt_v0.bin version: 16.92.21.p81

iw611-bt / iw612-bt:
uartspi_n61x_v1.bin.se version: 18.99.1.p154.40

These firmware files are downloaded over UART interface. The
helper_uart_3000000.bin needs to be downloaded before
uartuart8997_bt_v4.bin for 88w8997 chip to set download baudrate
to 3000000.

The above commit message is copied from the source commit message:
https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/commit/nxp?id=1f82dd25c3ea59b6bed80ee685d860f0c5f19875

Signed-off-by: Tom Hochstein <tom.hochstein@nxp.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>