Use a define for a9mpcore_priv device type name instead of hard-coded
string.
Signed-off-by: NKrzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>