drivers: intc: esp32: Shared allocator for Xtensa and RISCV

Update interrupt allocator to use the same driver for both
Xtensa and RISCV devices.

Signed-off-by: Raffael Rostagno <raffael.rostagno@espressif.com>
Signed-off-by: Sylvio Alves <sylvio.alves@espressif.com>