Revert "ath10k: add sanity check to ie_len before parsing fw/board ie"

This reverts commit 9ed4f916

.

The commit introduced a regression that over read the ie with
the padding.

- the expected IE information

ath10k_pci 0000:03:00.0: found firmware features ie (1 B)
ath10k_pci 0000:03:00.0: Enabling feature bit: 6
ath10k_pci 0000:03:00.0: Enabling feature bit: 7
ath10k_pci 0000:03:00.0: features
ath10k_pci 0000:03:00.0: 00000000: c0 00 00 00 00 00 00 00

- the wrong IE with padding is read (0x77)

ath10k_pci 0000:03:00.0: found firmware features ie (4 B)
ath10k_pci 0000:03:00.0: Enabling feature bit: 6
ath10k_pci 0000:03:00.0: Enabling feature bit: 7
ath10k_pci 0000:03:00.0: Enabling feature bit: 8
ath10k_pci 0000:03:00.0: Enabling feature bit: 9
ath10k_pci 0000:03:00.0: Enabling feature bit: 10
ath10k_pci 0000:03:00.0: Enabling feature bit: 12
ath10k_pci 0000:03:00.0: Enabling feature bit: 13
ath10k_pci 0000:03:00.0: Enabling feature bit: 14
ath10k_pci 0000:03:00.0: Enabling feature bit: 16
ath10k_pci 0000:03:00.0: Enabling feature bit: 17
ath10k_pci 0000:03:00.0: Enabling feature bit: 18
ath10k_pci 0000:03:00.0: features
ath10k_pci 0000:03:00.0: 00000000: c0 77 07 00 00 00 00 00

Tested-by: Mike Lothian <mike@fireburn.co.uk>
Signed-off-by: Ryan Hsu <ryanhsu@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>