ath11k: Remove rproc references from common core layer

IPQ8074 HW uses rproc with AHB as underlying hif layer.
Move rproc references from common core layer to target
hif layer. Remove IS_ENABLED check for CONFIG_REMOTEPROC
as it's not required anymore.

No functional changes. Compile tested only.

Signed-off-by: Govind Singh <govinds@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1600090615-18904-1-git-send-email-govinds@codeaurora.org