e1000: remove unnecessary clearing of SWSM.SWSM_SMBI

e1000: remove unnecessary clearing of SWSM.SWSM_SMBI

remove unnecessary clearing of SWSM.SWSM_SMBI when obtaining the SW
semaphore. This was introduced in 951860634fdb557bbb58e0f99215391bc0c29779
while adding i210 support and should be now resolved by releasing the
semaphore when no longer needed.

Cc: Marcel Ziswiler <marcel@ziswiler.com>
Cc: Marek Vasut <marex@denx.de>
Cc: Aneesh Bansal <aneesh.bansal@freescale.com>
Cc: Naveen Burmi <NaveenBurmi@freescale.com>
Cc: Po Liu <po.liu@freescale.com>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Alison Wang <alison.wang@freescale.com>
Cc: Reinhard Arlt <reinhard.arlt@esd-electronics.com>
Cc: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Cc: York Sun <yorksun@freescale.com>
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>