ravb: Add ESF in RCR for enabling separation filter

The H/W manual recommends B'10 or B'11 in a value of the separation
filtering select bits in the receive configuration register (RCR.ESF).
When B'10 is set, frames from non-matching streams are discarded.
When B'11 is set, frames from non-matching streams are processed in
reception queue 0 (best effort).
This patch sets B'11 in ESF.

[ykaneko0929@gmail.com: revised this commit message]
Signed-off-by: Masaru Nagai <masaru.nagai.vx@renesas.com>
Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com>
Acked-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>