sh_eth: use correct name for ECMR_MPDE bit

sh_eth: use correct name for ECMR_MPDE bit

[ Upstream commit 6dcf45e514974a1ff10755015b5e06746a033e5f ]

This bit was wrongly named due to a typo, Sergei checked the SH7734/63
manuals and this bit should be named MPDE.

Suggested-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>