ath10k: sdio: use same endpoint id for all packets in a bundle

All packets in a bundle should use the same endpoint id as the
first lookahead.

This matches how things are done is ath6kl, however,
this patch can theoretically handle several bundles
in ath10k_sdio_mbox_rx_process_packets().

Without this patch we get lots of errors about invalid endpoint id:

ath10k_sdio mmc2:0001:1: invalid endpoint in look-ahead: 224
ath10k_sdio mmc2:0001:1: failed to get pending recv messages: -12
ath10k_sdio mmc2:0001:1: failed to process pending SDIO interrupts: -12

Co-Developed-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Alagu Sankar <alagusankar@silex-india.com>
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>