lib: sbi: Simplify ipi platform operations

Instead of having ipi_send() and ipi_clear() callbacks in
platform operations, it will be much simpler for ipi driver
to directly register these operations as a device to sbi_ipi
implementation.

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

lib/sbi/sbi_hsm.c

@@ -238,7 +238,7 @@ int sbi_hsm_hart_start(struct sbi_scratch *scratch,
 		return sbi_platform_hart_start(plat, hartid,
 					       scratch->warmboot_addr);
 	} else {
-		sbi_platform_ipi_send(plat, hartid);
+		sbi_ipi_raw_send(hartid);
 	}
 
 	return 0;