wilc1000: Add support for enabling CRC

The driver so far has always disabled CRC protection. This means any
data corruption that occurrs during the SPI transfers could go
undetected. This patch adds module parameters enable_crc7 and
enable_crc16 to selectively turn on CRC7 (for command transfers) and
CRC16 (for data transfers), respectively.

The default configuration remains unchanged, with both CRC7 and CRC16
off.

The performance impact of CRC was measured by running ttcp -t four
times in a row on a SAMA5 device:

CRC7 CRC16 Throughput: Standard deviation:
---- ----- ----------- -------------------
off off 1720 +/- 48 KB/s
on off 1658 +/- 58 KB/s
on on 1579 +/- 84 KB/s

Signed-off-by: David Mosberger-Tang <davidm@egauge.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210227172818.1711071-4-davidm@egauge.net

wilc1000: fix spelling mistake in Kconfig "devision" -> "division"

There is a spelling mistake in the Kconfig help text. Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201216115808.12987-1-colin.king@canonical.com

wilc1000: move wilc driver out of staging

WILC1000 is an IEEE 802.11 b/g/n IoT link controller module. The
WILC1000 connects to Microchip AVR/SMART MCUs, SMART MPUs, and other
processors with minimal resource requirements with a simple
SPI/SDIO-to-Wi-Fi interface.

WILC1000 driver has been part of staging for few years. With
contributions from the community, it has improved significantly. Full
driver review has helped in achieving the current state.
The details for those reviews are captured in 1 & 2.

[1]. https://lore.kernel.org/linux-wireless/1537957525-11467-1-git-send-email-ajay.kathat@microchip.com/
[2]. https://lore.kernel.org/linux-wireless/1562896697-8002-1-git-send-email-ajay.kathat@microchip.com/

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>