irqchip/riscv-intc: Fix SMP=n boot with ACPI

When CONFIG_SMP is disabled, the static array rintc_acpi_data with size
NR_CPUS is not sufficient to hold all RINTC structures passed from the
firmware.

All RINTC structures are required to configure IMSIC/APLIC/PLIC properly
irrespective of SMP in the OS. So, allocate dynamic memory based on the
number of RINTC structures in MADT to fix this issue.

Fixes: f8619b66 ("irqchip/riscv-intc: Add ACPI support for AIA")
Reported-by: Björn Töpel <bjorn@kernel.org>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/all/20241014065739.656959-1-sunilvl@ventanamicro.com
Closes: https://github.com/linux-riscv/linux-riscv/actions/runs/11280997511/job/31375229012