Tidy up, remove MPI_CORE(), apply the naming convention, and use the new mbedtls_mpi_core_mul()

Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/bignum_core.c b/library/bignum_core.c
index 1ec5340..1ba4142 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -448,13 +448,15 @@
     return c;
 }
 
-void MPI_CORE(mul)( mbedtls_mpi_uint *X,
-                    const mbedtls_mpi_uint *A, size_t a,
-                    const mbedtls_mpi_uint *B, size_t b )
+void mbedtls_mpi_core_mul(mbedtls_mpi_uint *X,
+                          const mbedtls_mpi_uint *A, size_t A_limbs,
+                          const mbedtls_mpi_uint *B, size_t B_limbs)
 {
-    memset( X, 0, ( a + b ) * ciL );
-    for( size_t i=0; i < b; i++ )
-        (void) mbedtls_mpi_core_mla( X + i, a + 1, A, a, B[i] );
+    memset(X, 0, (A_limbs + B_limbs) * ciL);
+
+    for (size_t i = 0; i < B_limbs; i++) {
+        (void) mbedtls_mpi_core_mla(X + i, A_limbs + 1, A, A_limbs, B[i]);
+    }
 }
 
 /*