juno/debug_rom: Fix order of set/enable debug isr

Currently interrupts CDBG_PWR_UP_REQ_IRQ, CDBG_RST_REQ_IRQ
and CSYS_PWR_UP_REQ_IRQ are enabled before setup, which is wrong.
Move enabling of these interrupts after calls to fwk_interrupt_set_isr

Change-Id: I9a583e22e2b500770ec448e6e9aea72f9098a2a0
Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>
Signed-off-by: Raphael Gault <raphael.gault@arm.com>
Signed-off-by: Girish Pathak <girish.pathak@arm.com>