net: stmmac: add clocks management for gmac driver

commit 5ec55823 upstream.

This patch intends to add clocks management for stmmac driver:

If CONFIG_PM enabled:
1. Keep clocks disabled after driver probed.
2. Enable clocks when up the net device, and disable clocks when down
the net device.

If CONFIG_PM disabled:
Keep clocks always enabled after driver probed.

Note:
1. It is fine for ethtool, since the way of implementing ethtool_ops::begin
in stmmac is only can be accessed when interface is enabled, so the clocks
are ticked.
2. The MDIO bus has a different life cycle to the MAC, need ensure
clocks are enabled when _mdio_read/write() need clocks, because these
functions can be called while the interface it not opened.

Stable backport notes:
When run below command to remove ethernet driver on
stratix10 platform, there will be warning trace as below:

$ cd /sys/class/net/eth0/device/driver/
$ echo ff800000.ethernet > unbind

WARNING: CPU: 3 PID: 386 at drivers/clk/clk.c:810 clk_core_unprepare+0x114/0x274
Modules linked in: sch_fq_codel
CPU: 3 PID: 386 Comm: sh Tainted: G        W         5.10.74-yocto-standard #1
Hardware name: SoCFPGA Stratix 10 SoCDK (DT)
pstate: 00000005 (nzcv daif -PAN -UAO -TCO BTYPE=--)
pc : clk_core_unprepare+0x114/0x274
lr : clk_core_unprepare+0x114/0x274
sp : ffff800011bdbb10
clk_core_unprepare+0x114/0x274
 clk_unprepare+0x38/0x50
 stmmac_remove_config_dt+0x40/0x80
 stmmac_pltfr_remove+0x64/0x80
 platform_drv_remove+0x38/0x60
 ... ..
 el0_sync_handler+0x1a4/0x1b0
 el0_sync+0x180/0x1c0
This issue is introduced by introducing upstream commit 8f269102
("net: stmmac: disable clocks in stmmac_remove_config_dt()")

But in latest mainline kernel, there is no this issue. Because this
patch improved clocks management for stmmac driver.
Therefore, backport it and its fixing patches to stable kernel v5.10.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: stable@vger.kernel.org
Signed-off-by: Meng Li <Meng.Li@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>