xtensa: update HAL path for custom compilations

Xtensa arch layer has some custom compilation commands to
generate the interrupt dispatchers and the core-isa* files.
However, the include path to find core-isa.h does not work
for Espressif ESP32. So update the mechanism to use correct
path pointing to Espressif HAL when targeting ESP32 family
SoCs.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>