FSP: Remove flash hook after completing code update

In some corner cases, FSP may not respond to Deep IPL request after
code update -OR- it may delay processing MBOX command. In such cases
we may enter code update path again.. which is not required.
Hence clear flash hook after completing code update.

Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

platforms/ibm-fsp/common.c

@@ -200,6 +200,9 @@ int64_t ibm_fsp_cec_reboot(void)
 	    fsp_flash_term_hook() == OPAL_SUCCESS)
 		cmd = FSP_CMD_DEEP_REBOOT;
 
+	/* Clear flash hook */
+	fsp_flash_term_hook = NULL;
+
 	printf("FSP: Sending 0x%02x reboot command to FSP...\n", cmd);
 
 	/* If that failed, talk to the FSP */
@@ -228,6 +231,9 @@ int64_t ibm_fsp_cec_power_down(uint64_t request)
 	if (fsp_flash_term_hook)
 		fsp_flash_term_hook();
 
+	/* Clear flash hook */
+	fsp_flash_term_hook = NULL;
+
 	printf("FSP: Sending shutdown command to FSP...\n");
 
 	if (fsp_sync_msg(fsp_mkmsg(FSP_CMD_POWERDOWN_NORM, 1, request), true))