brcmfmac: correct logging levels in btcoex source

All log messages were set to TRACE level, which is intended
for function entry and exit. Using INFO instead in other
places. Also reducing an error message that always popped
up upon module unload.

Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>