The pxa-impedance-matcher is a 3rd stage loader that is used to boot
legacy hardware that has a bootloader which is unable to boot DT kernels.

It acts as chain loader which determines the correct hardware type and DTB
blob.

You should disable CONFIG_ARM_APPENDED_DTB in your kernel config.  The
impedance-matcher should be viewed as a replacement for that option.

It used to be completetly specific to PXA3xx based Raumfeld hardware, but
was turned into a more generic kind of framework recently.

WARNING: PLEASE ONLY USE THIS TOOL AS A LAST RESORT OPTION FOR LEGACY
HARDWARE, AND NOT AS AN OPTION FOR NEW DEVELOPMENTS. THE CLEARLY ADVISED
WAY IS TO ADD PROPER DTB SUPPORT TO YOUR BOOTLOADER.