nfc: port100: correct kerneldoc for structure

nfc: port100: correct kerneldoc for structure

The port100_in_rf_setting structure does not contain valid kerneldoc
docummentation, unlike the port100_tg_rf_setting structure.  Correct the
kerneldoc to fix W=1 warnings:

    warning: This comment starts with '/**', but isn't a kernel-doc comment.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20210528124200.79655-3-krzysztof.kozlowski@canonical.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>