ath11k: allocate smaller chunks of memory for firmware

On x86 it's sometimes difficult to allocate a large contigous DMA
memory, so instead allocate blocks of small chunk memory.

In ath11k_qmi_msg_mem_request_cb() the error handling was cleaned up to avoid
an unused variable warning. Also changed the test from (ret < 0) to just (ret)
as the functions don't return any positive values.

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: Carl Huang <cjhuang@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1597389030-13887-8-git-send-email-kvalo@codeaurora.org