net: stmmac: use unsigned int for eee_timer

net: stmmac: use unsigned int for eee_timer

Since eee_timer is used to initialise priv->tx_lpi_timer, this also
should be unsigned to avoid a negative number being interpreted as a
very large positive number. Note that this makes the check for negative
numbers passed in as a module parameter redundant, and passing a
negative number will now produce a large delay rather than the
default. Since the default is used without an argument, passing a
negative number would be quite obscure. However, if users do, then
this will need to be revisited.

Reviewed-by: Simon Horman <horms@kernel.org>
Tested-by: Choong Yong Liang <yong.liang.choong@linux.intel.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1tVZDh-0002K3-6y@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>