Bluetooth: btintel_pcie: Reduce driver buffer posting to prevent race condition

Modify the driver to post 3 fewer buffers than the maximum rx buffers
(64) allowed for the firmware. This change mitigates a hardware issue
causing a race condition in the firmware, improving stability and data
handling.

Signed-off-by: Chandrashekar Devegowda <chandrashekar.devegowda@intel.com>
Signed-off-by: Kiran K <kiran.k@intel.com>
Fixes: c2b636b3 ("Bluetooth: btintel_pcie: Add support for PCIe transport")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>