hw/intc/aspeed: Introduce dynamic allocation for regs array

hw/intc/aspeed: Introduce dynamic allocation for regs array

Currently, the size of the "regs" array is 0x2000, which is too large. To save
code size and avoid mapping large unused gaps, will update it to only map the
useful set of registers. This update will support multiple sub-regions with
different sizes.

To address the redundant size issue, replace the static "regs" array with a
dynamically allocated "regs" memory.

Introduce a new "aspeed_intc_unrealize" function to free the allocated "regs"
memory.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250307035945.3698802-4-jamin_lin@aspeedtech.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>