fix(zynqmp): fix length of clock name

The CLK_NAME_LEN variable is set to 15 but with more
hardening we get the following error for the
pss_alt_ref_clk name so bump the length slightly
to take all the requirements into account.

plat/xilinx/zynqmp/pm_service/pm_api_clock.c:2248:25: error: initializer-string for array of ‘char’ is too long [-Werror=unterminated-string-initialization]
2248 |                 .name = "pss_alt_ref_clk",
     |                         ^~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Fixes: caae497df ("zynqmp: pm: Add clock control EEMI API and ioctl functions")
Change-Id: I399271dd257c6e40a2d319c47f2588a958a5491b
Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
diff --git a/plat/xilinx/zynqmp/pm_service/pm_api_clock.h b/plat/xilinx/zynqmp/pm_service/pm_api_clock.h
index 3498f91..89031b8 100644
--- a/plat/xilinx/zynqmp/pm_service/pm_api_clock.h
+++ b/plat/xilinx/zynqmp/pm_service/pm_api_clock.h
@@ -15,7 +15,7 @@
 
 #include "pm_common.h"
 
-#define CLK_NAME_LEN		(15U)
+#define CLK_NAME_LEN		(16U)
 #define MAX_PARENTS		(100U)
 #define CLK_NA_PARENT		-1
 #define CLK_DUMMY_PARENT	-2