This commit adds 6xx specific interrupt support, some register offsets and
bitmasks differ from 4xx, which we account for in this commit.

[bod: Added commit log. Moved register definition into commit]
Signed-off-by: Dikshita Agarwal <dikshita@codeaurora.org>
Co-developed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>