net: stmmac: Use mutex instead of spinlock

net: stmmac: Use mutex instead of spinlock

Some drivers, such as DWC EQOS on Tegra, need to perform operations that
can sleep under this lock (clk_set_rate() in tegra_eqos_fix_speed()) for
proper operation. Since there is no need for this lock to be a spinlock,
convert it to a mutex instead.

Fixes: e6ea2d16fc61 ("net: stmmac: dwc-qos: Add Tegra186 support")
Reported-by: Jon Hunter <[email protected]>
Signed-off-by: Thierry Reding <[email protected]>
Tested-by: Bhadram Varka <[email protected]>
Signed-off-by: David S. Miller <[email protected]>