Correctly include cblas include directories

RHEL uses a dedicated cblas include directory. Correctly include this
for the one target PHY_UE that relies on this.

Co-authored-by: Robert Schmidt <robert.schmidt@openairinterface.org>

openair1/PHY/LTE_UE_TRANSPORT/linear_preprocessing_rec.c

@@ -12,11 +12,7 @@ data storage. */
 #include<complex.h>
 #include <stdlib.h>
 #include <linux/version.h>
-#if defined RHEL_RELEASE_CODE
-#include <cblas/cblas.h>
-#else
 #include <cblas.h>
-#endif
 #include <string.h>
 #include <linux/version.h>
 #include <lapacke_utils.h>