GIC: Add API to get running priority

Document the API in separate platform interrupt controller API document.

Change-Id: If18f208e10a8a243f5c59d226fcf48e985941949
Co-authored-by: Yousuf A <yousuf.sait@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/include/lib/aarch32/arch_helpers.h b/include/lib/aarch32/arch_helpers.h
index 5d31836..1f4f216 100644
--- a/include/lib/aarch32/arch_helpers.h
+++ b/include/lib/aarch32/arch_helpers.h
@@ -257,6 +257,7 @@
 DEFINE_COPROCR_RW_FUNCS(icc_sre_el2, ICC_HSRE)
 DEFINE_COPROCR_RW_FUNCS(icc_sre_el3, ICC_MSRE)
 DEFINE_COPROCR_RW_FUNCS(icc_pmr_el1, ICC_PMR)
+DEFINE_COPROCR_RW_FUNCS(icc_rpr_el1, ICC_RPR)
 DEFINE_COPROCR_RW_FUNCS(icc_igrpen1_el3, ICC_MGRPEN1)
 DEFINE_COPROCR_RW_FUNCS(icc_igrpen0_el1, ICC_IGRPEN0)
 DEFINE_COPROCR_RW_FUNCS(icc_hppir0_el1, ICC_HPPIR0)