staging: wfx: drop calls to BUG_ON()

Most of calls to BUG_ON() could replaced by WARN().

By the way, this patch also try to favor WARN() (that include a comment
about the problem) instead of WARN_ON().

Reported-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20191008094232.10014-7-Jerome.Pouiller@silabs.com


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