util/crossgcc: Add comment on IASL version

Change-Id: I81c6f4134610bcd35e173cdb002ef821788b0538
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38164
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

util/crossgcc/buildgcc

@@ -54,6 +54,10 @@ GCC_VERSION=8.3.0
 GCC_AUTOCONF_VERSION=2.69
 BINUTILS_VERSION=2.33.1
 GDB_VERSION=8.3.1
+
+# Conflicting use of _ADR and _HID in coreboot tree needs
+# to be properly addressed before we can upgrade IASL version.
+# Use IASL version 20190703 for now.
 IASL_VERSION=20190703
 PYTHON_VERSION=3.8.1
 EXPAT_VERSION=2.2.9