staging: wfx: relocate TX_RETRY_POLICY_MAX and TX_RETRY_POLICY_INVALID to hif API

The definitions TX_RETRY_POLICY_MAX and TX_RETRY_POLICY_INVALID are
imposed by the hardware. Therefore, they should be located in the
hardware interface API.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200406111756.154086-4-Jerome.Pouiller@silabs.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>