brcmfmac: simplify handling e-scan result firmware event

Upon handling an e-scan result event from the firmware in
brcmf_cfg80211_escan_handler() the status may indicate e-scan
is completed or aborted. If so brcmf_notify_escan_complete()
is called. However, that function and brcmf_cfg80211_escan_handler()
both log the same debug message and both enable MPC flag in the
firmware.

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