lib: sbi: Simplify console platform operations

Instead of having console_putc() and console_getc() callbacks in
platform operations, it will be much simpler for console driver to
directly register these operations as device to the sbi_console
implementation.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Xiang W <wxjstz@126.com>

include/sbi_utils/sys/htif.h

@@ -10,9 +10,7 @@
 
 #include <sbi/sbi_types.h>
 
-void htif_putc(char ch);
-
-int htif_getc(void);
+int htif_serial_init(void);
 
 int htif_system_reset_check(u32 type, u32 reason);