dm: acpi: Enhance acpi_get_name()

For many device types it is possible to figure out the name just by
looking at its uclass or parent. Add a function to handle this, since it
allows us to cover the vast majority of cases automatically.

However it is sometimes impossible to figure out an ACPI name for a device
just by looking at its uclass. For example a touch device may have a
vendor-specific name. Add a new "acpi,name" property to allow a custom
name to be created.

With this new feature we can drop the get_name() methods in the sandbox
I2C and SPI drivers. They were only added for testing purposes. Update the
tests to use the new values.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>