Move library/common.h to tf-psa-crypto/core directory

This commit moves common.h from library to tf-psa-crypto/core.

Signed-off-by: Harry Ramsey <harry.ramsey@arm.com>
diff --git a/library/common.h b/tf-psa-crypto/core/common.h
similarity index 100%
rename from library/common.h
rename to tf-psa-crypto/core/common.h