[ Upstream commit 556a0964e28c4441dcdd50fb07596fd042246bd5 ] The mailbox length is 0x1000 hence the max_register value is 0xFFC. Fixes: c6a8b171ca8e ("mailbox: qcom: Convert APCS IPC driver to use regmap") Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org> Signed-off-by: Sasha Levin <sashal@kernel.org>