Enable ArmadaXP using INTRNG interrupt controller

Defining INTRNG remove some necessary registers and declarations of
pic_init_secondary, pic_ipi_send, pic_ipi_read and pic_ipi_clear.
Because Marvell ArmadaXP and Armada38X always use INTRNG, include all
INTRNG code and remove code that does not use it.
Separate pic registers declarations for Armada38X are unnecessary, it
works properly with ArmadaXP config.

Submitted by: Rafal Kozik <rk@semihalf.com>
Reviewed by: andrew
Obtained from: Semihalf
Sponsored by: Stormshield
Differential Revision: https://reviews.freebsd.org/D14734