staging: r8822be: fix null pointer dereference with a null driver_adapter

The call to _rtl_dbg_trace via macro HALMAC_RT_TRACE will trigger a null
pointer deference on the null driver_adapter.  Fix this by assigning
driver_adapter earlier to halmac_adapter->driver_adapter before the tracing
call so that a non-null driver_adapter is passed instead.

Detected by CoverityScan, CID#1454613 ("Explicit null dereferenced")

Fixes: 938a0447 ("staging: r8822be: Add code for halmac sub-driver")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>