greybus: sdio: clarify operator precedence

When translating capabilities from greybus to mmc values add some
parentheses to clarify operation precedence and avoid static analyses
warnings.

[sdio.c:81]: (style) Clarify calculation precedence for '&' and '?'

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>