lib: sbi: Simplify timer platform operations

Instead of having timer_value(), timer_event_start(), and
timer_event_stop() callbacks in platform operations, it will
be much simpler for timer driver to directly register these
operations as device to the sbi_timer implementation.

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

lib/sbi/sbi_platform.c

@@ -19,9 +19,6 @@ static inline char *sbi_platform_feature_id2string(unsigned long feature)
 		return NULL;
 
 	switch (feature) {
-	case SBI_PLATFORM_HAS_TIMER_VALUE:
-		fstr = "timer";
-		break;
 	case SBI_PLATFORM_HAS_HART_HOTPLUG:
 		fstr = "hotplug";
 		break;