irqchip/mbigen: Fix mbigen node address layout

irqchip/mbigen: Fix mbigen node address layout

The mbigen interrupt chip has its per node registers located in a
contiguous region of page sized chunks. The code maps them into virtual
address space as a contiguous region and determines the address of a node
by using the node ID as index.

                    mbigen chip
       |-----------------|------------|--------------|
   mgn_node_0         mgn_node_1     ...         mgn_node_i
|--------------|   |--------------|       |----------------------|
[0x0000, 0x0x0FFF] [0x1000, 0x1FFF]    [i*0x1000, (i+1)*0x1000 - 1]

This works correctly up to 10 nodes, but then fails because the 11th's
array slot is used for the MGN_CLEAR registers.

                         mbigen chip
    |-----------|--------|--------|---------------|--------|
mgn_node_0  mgn_node_1  ...  mgn_clear_register  ...   mgn_node_i
                            |-----------------|
                             [0xA000, 0xAFFF]

Skip the MGN_CLEAR register space when calculating the offset for node IDs
greater than or equal to ten.

Fixes: a6c2f87b8820 ("irqchip/mbigen: Implement the mbigen irq chip operation functions")
Signed-off-by: Yipeng Zou <zouyipeng@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240730014400.1751530-1-zouyipeng@huawei.com