gpio: davinci: correct non-kerneldoc comment

Drop kerneldoc annotation from regular comment to fix:

  gpio-davinci.c:716: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>