drivers: net: xgene: Fix module unload crash - clkrst sequence

drivers: net: xgene: Fix module unload crash - clkrst sequence

BugLink: https://launchpad.net/bugs/1632739
This patch fixes clock reset sequence.

- Added clock reset sequence for ACPI
- Added delay in clock reset sequence to make sure pulse is generated
- Added clk_unprepare_disable() in port shutdown to make sure
  clock increment/decrement counts are matching
- Removed MII_MGMT_CONFIG programming, since it is not required
- Fixed programming XGENET_CONFIG_REG to enable SGMII mode

Signed-off-by: Iyappan Subramanian <isubramanian@apm.com>
Tested-by: Fushen Chen <fchen@apm.com>
Tested-by: Toan Le <toanle@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit bc61167ac816621c94f722177d2ae718c103005f yakkety)
Signed-off-by: Craig Magina <craig.magina@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>