defconfig: sdm855: enable PMIC clock divider driver

Enable the SPMI PMIC clock divider driver so that consumers can
control XO clock dividers found on PMIC chips.

Change-Id: I16aba7b422fd1ed5ef0fc7c60e897d685ffb38a0
Signed-off-by: David Collins <collinsd@codeaurora.org>