linux-postmarketos-mediatek-mt8173: upgrade to 6.11 and remove patches

the patches fix-mmc1-speed and fix-spi-nor-max-frequency have been
removed from the source (aports/testing/google-elm) for a while, and
I've run a personal build of 6.10 for a bit with them removed with no
perceived negative side effects.

disabling powervr temporarily to test if it un-breaks the video.