Can you add
CONFIG_WL12XX_SDIO_TEST=m
(network 80211 configuration parameter)
to the power kernel ?
It seems this is what is needed to get injection working, together with either iwconfig or macchanger MAC.
I compiled it as a module to be able to test (able to load/unload) together with 80211 compiled as a module, like the power kernel.
I guess it could be compiled as 'y', but, I believe being able to load on need can save battery power