Documentation: msm: Add compatible strings for pinctrl documentation

Update the list of compatible strings for the pinctrl documentation
	"qcom,msm8952-pinctrl"
	"qcom,msmtitanium-pinctrl"
	"qcom,msmthorium-pinctrl"

Change-Id: Ie4428ebe254040d82312a5c72a5e70b2ac32d1ae
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>