Reset EL2 and EL3 configurable controls

This patch resets EL2 and EL3 registers that have architecturally
UNKNOWN values on reset and that also provide EL2/EL3 configuration
and trap controls.

Specifically, the EL2 physical timer is disabled to prevent timer
interrups into EL2 - CNTHP_CTL_EL2 and CNTHP_CTL for AArch64 and AArch32,
respectively.

Additionally, for AArch64, HSTR_EL2 is reset to avoid unexpected traps of
non-secure access to certain system registers at EL1 or lower.

For AArch32, the patch also reverts the reset to SDCR which was
incorrectly added in a previous change.

Change-Id: If00eaa23afa7dd36a922265194ccd6223187414f
Signed-off-by: David Cunado <david.cunado@arm.com>
diff --git a/include/lib/aarch32/arch_helpers.h b/include/lib/aarch32/arch_helpers.h
index 0633bca..7955d62 100644
--- a/include/lib/aarch32/arch_helpers.h
+++ b/include/lib/aarch32/arch_helpers.h
@@ -250,6 +250,7 @@
 DEFINE_COPROCR_RW_FUNCS(icc_eoir1_el1, ICC_EOIR1)
 
 DEFINE_COPROCR_RW_FUNCS(hdcr, HDCR)
+DEFINE_COPROCR_RW_FUNCS(cnthp_ctl, CNTHP_CTL)
 DEFINE_COPROCR_READ_FUNC(pmcr, PMCR)
 
 /*