hw/sd: Use sdbus_read_data() instead of sdbus_read_byte() when possible

Use the recently added sdbus_read_data() to read multiple
bytes at once, instead of looping calling sdbus_read_byte().

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200814092346.21825-8-f4bug@amsat.org>
3 files changed