ARM: uniphier: remove #include <net.h> again from micro-support-card.c

I do not understand the changes made to this file by
commit 90526e9f ("common: Drop net.h from common header").

  git show 90526e9f -- arch/arm/mach-uniphier/micro-support-card.c

The necessary declaration is already included by <netdev.h> at line 112.
It also moved the <dm/of.h> inclusion, but I do not understand the
motivation of doing so, either.

Simply revert the changes made to this file.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>