Revert "ns16650: Make sure we have CONFIG_CLK set before using infrastructure"

This reverts commit 82f5279b.

The build failure of k2*evm boards was fixed in a different way by
the previous commit.  It is nasty to patch generic drivers around
with #ifdef CONFIG_CLK just for the KeyStone's matter.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>