serial: lpc32xx: allow compile testing

The lpc32xx_loopback_set() function in hte lpc32xx_hs driver is the
one thing that relies on platform header files. Move that into the
core platform code so we only need a variable declaration for it,
and enable COMPILE_TEST building.

Link: https://lore.kernel.org/r/20190809144043.476786-12-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

net: lpc-enet: move phy setup into platform code

Setting the phy mode requires touching a platform specific
register, which prevents us from building the driver without
its header files.

Move it into a separate function in arch/arm/mach/lpc32xx
to hide the core registers from the network driver.

Link: https://lore.kernel.org/r/20190809144043.476786-8-arnd@arndb.de
Acked-by: Sylvain Lemieux <slemieux.tyco@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

net: lpc-enet: factor out iram access

The lpc_eth driver uses a platform specific method to find
the internal sram. This prevents building it on other machines.

Rework to only use one function call and keep the other platform
internals where they belong. Ideally this would look up the
sram location from DT, but as this is a rarely used driver,
I want to keep the modifications to a minimum.

Link: https://lore.kernel.org/r/20190809144043.476786-7-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>