CONFIG_IOMEM does not exist.  The correct symbol to depend on is
CONFIG_HAS_IOMEM.

Fixes: 1e7468bd ("clk: Specify IOMEM dependency for HSDK pll driver")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200803084835.21838-1-geert+renesas@glider.beSigned-off-by: Stephen Boyd <sboyd@kernel.org>