ath11k: implement ath11k_core_pre_init()

This is needed to initialise hw_params before MHI registration starts. MHI
needs location of firmware directory and that's delivered via hw_params.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1
Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.1.0.1-01238-QCAHKSWPL_SILICONZ-2

Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1597309466-19688-8-git-send-email-kvalo@codeaurora.org