ARM: imx: fix ksz9021rn_phy_fixup

The ksz9021rn_phy_fixup and mx6q_sabrelite functions try to
set up an ethernet phy if they can. They do check whether
phylib is enabled, but unfortunately the functions can only
be called from platform code if phylib is builtin, not
if it is a module

Without this patch, building with a modular phylib results in:

arch/arm/mach-imx/mach-imx6q.c: In function 'imx6q_sabrelite_init':
arch/arm/mach-imx/mach-imx6q.c:120:5: error: 'ksz9021rn_phy_fixup' undeclared (first use in this function)
arch/arm/mach-imx/mach-imx6q.c:120:5: note: each undeclared identifier is reported only once for each function it appears in

The bug was originally reported by Artem Bityutskiy but only
partially fixed in ef441806 "ARM: imx6q: register phy fixup only when
CONFIG_PHYLIB is enabled".

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Artem Bityutskiy <dedekind1@gmail.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>