net: phy: ar803x: disable extended next page bit

This bit is enabled by default and advertises support for extended
next page support.  XNP is only needed for 10GBase-T and MultiGig
support which is not supported. Additionally, Cisco MultiGig switches
will read this bit and attempt 10Gb negotiation even though Next Page
support is disabled. This will cause timeouts when the interface is
forced to 100Mbps and auto-negotiation will fail. The interfaces are
only 1000Base-T and supporting auto-negotiation for this only requires
the Next Page bit to be set.

Taken from:
https://github.com/SolidRun/linux-stable/commit/7406c5244b7ea6bc17a2afe8568277a8c4b126a9


and adapted to mainline kernels by rmk.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/E1kzSdb-000417-FJ@rmk-PC.armlinux.org.uk


Signed-off-by: Jakub Kicinski <kuba@kernel.org>