net: phy: Fixup GPLv2 SPDX tags based on license text

A few PHY drivers have the GPLv2 license text. They then either have
a MODULE_LICENSE() of GPLv2+, or an SPDX tag of GPLv2+.

Since the license text is much easier to understand than either the
SPDX tag or the MODULE_LICENSE, use it as the definitive source of the
licence, and fixup with others when there are contradictions.

Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Jonas Jensen <jonas.jensen@gmail.com>
Cc: Laurent Pinchart <laurentp@cse-semaphore.com>
Cc: Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
Cc: Scott Wood <scottwood@freescale.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Andrew F. Davis <afd@ti.com>
Acked-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>