ipq806x: disable i2c device on gsbi4

Patch cherry-picked from the following location:
https://chromium-review.googlesource.com/#/c/269931/



Disable the i2c device on gsbi4 and mark gsbi4_h and gsbi4_qup clks as
unused. If they are enabled, clock framework will turn them off at end
of probe. On ipq806x by design gsbi4_qup, gsbi4_h clks and i2c on gsbi4
are meant for RPM usage. So turning them off in kernel is incorrect.

Signed-off-by: Mathieu Olivari <mathieu@codeaurora.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45728 3c298f89-4303-0410-b956-a3cf2f4a3e73