mmc: sdhci-bcm-kona: fix logic to check for 8-bit data width

The driver prints if the data width is 8-bit but it's using a
binary OR instead of a binary AND so it will always report as
"is_8bit=Y" regardless of the flags in host->mmc->caps.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Ray Jui <rjui@broadcom.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>