arch: arm: aarch32: fix irq.h include sequence

It turns out we could end up with a circular include dependency through
the following sequences:

zephyr/arch/arm/aarch32/irq.h:19 -> zephyr/irq.h
zephyr/arch/arm/aarch32/arch.h:27
zephyr/arch/cpu.h:19
zephyr/sys/arch_interface.h:33
zephyr/timing/timing.h:10

or

zephyr/arch/arm/aarch32/asm_inline_gcc.h:23 -> zephyr/irq.h
zephyr/arch/arm/aarch32/asm_inline.h
zephyr/arch/arm/aarch32/irq.h:19
zephyr/arch/arm/aarch32/arch.h:27
zephyr/arch/cpu.h:19
zephyr/sys/arch_interface.h:33
zephyr/timing/timing.h:10

The problem is that both aarch32 irq.h/asm_inline_gcc.h include
zephyr/irq.h (which in turn depends on the arch specific header, as it
should be). So arch_irq_connect_dynamic ended up being used before its
declaration.

This patch removes zephyr/irq.h from the aarch32 headers, as it makes no
sense to have such _reverse dependency_.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>