Bluetooth: hci_bcm: Add CYW4373A0 support

CYW4373A0 is a Wi-Fi + Bluetooth combo device from Cypress.
This chip is present e.g. on muRata 2AE module.

This chip has additional quirk where the HCI command 0xfc45, used on
older chips to switch UART clock from 24 MHz to 48 MHz, to support
baudrates over 3 Mbdps, is no longer recognized by this newer chip.
This newer chip can configure the 4 Mbdps baudrate without the need
to issue HCI command 0xfc45, so add flag to indicate this and do not
issue the command on this chip to avoid failure to set 4 Mbdps baud
rate.

It is not clear whether there is a way to determine which chip does
and which chip does not support the HCI command 0xfc45, other than
trial and error.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>