net: phy: export phy_error and phy_trigger_machine

These functions are currently used by phy_interrupt() to either signal
an error condition or to trigger the link state machine. In an attempt
to actually support shared PHY IRQs, export these two functions so that
the actual PHY drivers can use them.

Cc: Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc: Andre Edich <andre.edich@microchip.com>
Cc: Antoine Tenart <atenart@kernel.org>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dan Murphy <dmurphy@ti.com>
Cc: Divya Koppera <Divya.Koppera@microchip.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Hauke Mehrtens <hauke@hauke-m.de>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Kavya Sree Kotagiri <kavyasree.kotagiri@microchip.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Marco Felsch <m.felsch@pengutronix.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: Mathias Kresin <dev@kresin.me>
Cc: Maxim Kochetkov <fido_max@inbox.ru>
Cc: Michael Walle <michael@walle.cc>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Nisar Sayed <Nisar.Sayed@microchip.com>
Cc: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: Philippe Schenker <philippe.schenker@toradex.com>
Cc: Willy Liu <willy.liu@realtek.com>
Cc: Yuiko Oshino <yuiko.oshino@microchip.com>
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>