Unify parameter naming

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/bignum_new.c b/library/bignum_new.c
index 142d15d..8a75806 100644
--- a/library/bignum_new.c
+++ b/library/bignum_new.c
@@ -143,19 +143,19 @@
 }
 
 int mbedtls_mpi_mod_modulus_setup( mbedtls_mpi_mod_modulus *m,
-                                   mbedtls_mpi_uint *X,
-                                   size_t nx,
+                                   mbedtls_mpi_uint *p,
+                                   size_t pn,
                                    int ext_rep,
                                    int int_rep )
 {
     int ret = 0;
 
-    if ( X == NULL || m == NULL )
+    if ( p == NULL || m == NULL )
         return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
 
-    m->p = X;
-    m->n = nx;
-    m->plen = mbedtls_mpi_core_bitlen( X, nx );
+    m->p = p;
+    m->n = pn;
+    m->plen = mbedtls_mpi_core_bitlen( p, pn );
 
     switch( ext_rep )
     {