portable: aarch64_sre: Add support for vApplicationFPUSafeIRQHandler

portable: aarch64_sre: Add support for vApplicationFPUSafeIRQHandler

The application writer needs to name their IRQ handler as:
1. vApplicationIRQHandler if the IRQ handler does not use FPU registers.
2. vApplicationFPUSafeIRQHandler is the IRQ handler uses FPU registers.

When the application uses vApplicationFPUSafeIRQHandler, a default
implementation of vApplicationIRQHandler is used which stores FPU
registers and then calls vApplicationFPUSafeIRQHandler.

Note that recent versions of GCC may use FP/SIMD registers to optimize 16-bytes
copy and especially when using va_start()/va_arg() functions (e.g printing some thing
in IRQ handlers may trigger usage of FPU registers)

This implementation is heavily inspired by both the ARM_CA9 port and the ARM_CRx_No_GIC
port done in [1]

[1] https://github.com/FreeRTOS/FreeRTOS-Kernel/pull/1113

Signed-off-by: Marouen Ghodhbane <marouen.ghodhbane@nxp.com>