Change error description

1. Change error description to a clearer one.
2. Change value in the error codes ranges description.
diff --git a/library/error.c b/library/error.c
index 0a1c794..12902e3 100644
--- a/library/error.c
+++ b/library/error.c
@@ -827,7 +827,7 @@
 
 #if defined(MBEDTLS_PLATFORM_C)
     if( use_ret == -(MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED) )
-        mbedtls_snprintf( buf, buflen, "PLATFORM - Hardware failed platform operation" );
+        mbedtls_snprintf( buf, buflen, "PLATFORM - Hardware accelerator failed" );
 #endif /* MBEDTLS_PLATFORM_C */
 
 #if defined(MBEDTLS_POLY1305_C)