irqchip/aspeed-intc: Remove AST2700-A0 support

irqchip/aspeed-intc: Remove AST2700-A0 support

The existing AST2700 interrupt controller driver ("aspeed,ast2700-intc-ic")
was written against the A0 pre-production design.

From A1 onwards (retained in the A2 production silicon), the interrupt
fabric was re-architected: interrupt routing is programmable and interrupt
outputs can be directed to multiple upstream controllers (PSP GIC,
Secondary Service Processor (SSP) NVIC, Tertiary Service Processor (TSP)
NVIC, and Boot MCU interrupt controller). This design requires route
resolution and a controller hierarchy model which the A0 driver cannot
represent.

Remove driver support for A0 in favour of the driver for the A2 production
design.

Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260407-irqchip-v5-4-c0b0a300a057@aspeedtech.com