Rename structure elements

Use better names for structure elements and adopting the convention of
the other modules.

Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/bignum_mod.c b/library/bignum_mod.c
index 38aff9b..dfccaf4 100644
--- a/library/bignum_mod.c
+++ b/library/bignum_mod.c
@@ -47,10 +47,10 @@
                                    mbedtls_mpi_uint *p,
                                    size_t pn )
 {
-    if( pn < m->n || !mbedtls_mpi_core_lt_ct( m->p, p, pn ) )
+    if( pn < m->limbs || !mbedtls_mpi_core_lt_ct( m->p, p, pn ) )
         return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
 
-    r->n = m->n;
+    r->limbs = m->limbs;
     r->p = p;
 
     return( 0 );
@@ -61,7 +61,7 @@
     if ( r == NULL )
         return;
 
-    r->n = 0;
+    r->limbs = 0;
     r->p = NULL;
 }
 
@@ -71,8 +71,8 @@
         return;
 
     m->p = NULL;
-    m->n = 0;
-    m->plen = 0;
+    m->limbs = 0;
+    m->bits = 0;
     m->ext_rep = MBEDTLS_MPI_MOD_EXT_REP_INVALID;
     m->int_rep = MBEDTLS_MPI_MOD_REP_INVALID;
 }
@@ -95,8 +95,8 @@
     }
 
     m->p = NULL;
-    m->n = 0;
-    m->plen = 0;
+    m->limbs = 0;
+    m->bits = 0;
     m->ext_rep = MBEDTLS_MPI_MOD_EXT_REP_INVALID;
     m->int_rep = MBEDTLS_MPI_MOD_REP_INVALID;
 }
@@ -110,8 +110,8 @@
     int ret = 0;
 
     m->p = p;
-    m->n = pn;
-    m->plen = mbedtls_mpi_core_bitlen( p, pn );
+    m->limbs = pn;
+    m->bits = mbedtls_mpi_core_bitlen( p, pn );
 
     switch( ext_rep )
     {