ath11k: pci: add MODULE_FIRMWARE macros

I am trying to get the ath11k driver to work with VyOS and during the
build it tries to discover the firmware blobs which drivers require.

This doesn't work with ath11k because it doesn't use the MODULE_FIRMWARE
macro. This patch fixes that.

Signed-off-by: Devin Bayer <dev@doubly.so>
[kvalo@codeaurora.org: cleanup commit log, move to pci.c]
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201202182705.dhkml4nb4rf2vwav@orac