hw/sd/sdbus: Provide buffer size to sdbus_do_command()

hw/sd/sdbus: Provide buffer size to sdbus_do_command()

We provide to sdbus_do_command() a pointer to a buffer to be
filled with a varying number of bytes. By not providing the
buffer size, the callee can not check the buffer is big enough.
Pass the buffer size as argument to follow good practices.

sdbus_do_command() doesn't return any error, only the size filled
in the buffer. Convert the returned type to unsigned and remove
the few unreachable lines in callers.

This allow to check for possible overflow in sd_do_command().

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20250804133406.17456-4-philmd@linaro.org>