wifi: rsi: Avoid defines prefixed with CONFIG

Macros prefixed with CONFIG_ are intended to be defined only by
Kconfig scripts. Here we remove the prefix from the
CONFIG_AUTO_READ_MODE define to avoid confusion when reading the code.

This causes no change to functionality.

Signed-off-by: Peter Lafreniere <peter@n8pjl.ca>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230118185353.2422-1-peter@n8pjl.ca