hw/sd/sdhci: Rename usdhc_ functions

hw/sd/sdhci: Rename usdhc_ functions

The next patches will introduce eSDHC device models (big and little endian).
Prepare for that by renaming the functions. Also, this makes the code have
similar conventions as in Linux and U-Boot.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-ID: <20260112145418.220506-8-shentey@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>