Revert "Bump sb-signing-utils version to v0.4"

This reverts commit a4185c8c901f4f1dde6d701b42d18ac5b31baad3.

Reports have come in that on some build environments this causes
build failures like this one:

 --> crtSignedContainer.sh: Generating signing requests...

 *** glibc detected *** create-container: malloc(): memory corruption: 0x00000000006096e0 ***

So, we will revert for now until this can be root caused and fixed.

Reported-by: Mike Baiocchi <mbaiocch@us.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
diff --git a/openpower/package/sb-signing-utils/sb-signing-utils.mk b/openpower/package/sb-signing-utils/sb-signing-utils.mk
index 33890c0..9676ebf 100644
--- a/openpower/package/sb-signing-utils/sb-signing-utils.mk
+++ b/openpower/package/sb-signing-utils/sb-signing-utils.mk
@@ -8,7 +8,7 @@
 
 SB_SIGNING_UTILS_LICENSE = Apache-2.0
 SB_SIGNING_UTILS_LICENSE_FILES = LICENSE
-SB_SIGNING_UTILS_VERSION ?= v0.4
+SB_SIGNING_UTILS_VERSION ?= v0.3
 
 HOST_SB_SIGNING_UTILS_DEPENDENCIES = host-openssl