HSI: omap-ssi: move omap_ssi_port_update_fclk

After the clk change support, the ssi omap ssi core driver
now calls into the port driver to change fclk. This function
was previously inside of an #ifdef, because it was only used
when CONFIG_PM is enabled. Now it also gets used without
power management support:

drivers/hsi/built-in.o: In function `ssi_clk_event':
omap_ssi_port.c:(.text+0x1bf8): undefined reference to `omap_ssi_port_update_fclk'

This moves the function outside of the CONFIG_PM guard.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 4bcf7414 ("HSI: omap-ssi: add clk change support")
Signed-off-by: Sebastian Reichel <sre@kernel.org>