lib/hwfeatures-gcry: Introduce functions to manage hardware features

This commit introduces the generic functions to manage the hardware
features in libgcrypt. These functions are stubs for future
platform-specific implementations:
  - grub_gcry_hwf_enabled() returns __gcry_use_hwf which indicates if
    the hardware features are enabled specifically by grub_enable_gcry_hwf(),
  - grub_enable_gcry_hwf() invokes the architecture specific enablement
    functions and sets __gcry_use_hwf to true,
  - grub_reset_gcry_hwf() invokes the architecture specific reset
    functions and sets __gcry_use_hwf to false.

Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

include/grub/hwfeatures-gcry.h

@@ -0,0 +1,26 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2025  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HWF_GCRY_HEADER
+#define HWF_GCRY_HEADER 1
+
+extern bool grub_gcry_hwf_enabled (void);
+extern void grub_enable_gcry_hwf (void);
+extern void grub_reset_gcry_hwf (void);
+
+#endif /* HWF_GCRY_HEADER */