lib: sbi: Simplify system reset platform operations

Instead of having system_reset_check() and system_reset() callbacks
in platform operations, it will be much simpler for reset driver to
directly register these operations as a device to the sbi_system
implementation.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

include/sbi_utils/sys/htif.h

@@ -12,8 +12,6 @@
 
 int htif_serial_init(void);
 
-int htif_system_reset_check(u32 type, u32 reason);
-
-void htif_system_reset(u32 type, u32 reason);
+int htif_system_reset_init(void);
 
 #endif