brcmfmac: add e-scan support.

brcmfmac: add e-scan support.

This patch adds e-scan support (currently i-scan is in use). E-scan
is a more powerful and memory efficient method for scanning. E-scan
will be the default scan method and eventually, i-scan support will
be removed. The scan methods do not make any difference to the end-user.

Reviewed-by: Arend Van Spriel <[email protected]>
Reviewed-by: Franky (Zhenhui) Lin <[email protected]>
Reviewed-by: Pieter-Paul Giesberts <[email protected]>
Signed-off-by: Hante Meuleman <[email protected]>
Signed-off-by: Arend van Spriel <[email protected]>
Signed-off-by: John W. Linville <[email protected]>