coresight: tpdm: Fix build break due to uninitialised field

{CMB/DSB}_PATT_ENABLE_TS attributes do not use an "idx" field and never sets it.
But, since have full blown warning enabled in coresight, it triggerst the warning
on some of the newer compiler versions:

drivers/hwtracing/coresight/coresight-tpdm.c:1055:2: error: missing field 'idx' initializer [-Werror,-Wmissing-field-initializers]
 1055 |         DSB_PATT_ENABLE_TS,
      |         ^
drivers/hwtracing/coresight/coresight-tpdm.h:184:3: note: expanded from macro 'DSB_PATT_ENABLE_TS'
  184 |                 tpdm_patt_enable_ts(enable_ts,                  \
      |                 ^
drivers/hwtracing/coresight/coresight-tpdm.h:156:5: note: expanded from macro 'tpdm_patt_enable_ts'
  156 |            }                                                    \
      |            ^
drivers/hwtracing/coresight/coresight-tpdm.c:1109:2: error: missing field 'idx' initializer [-Werror,-Wmissing-field-initializers]
 1109 |         CMB_PATT_ENABLE_TS,
      |         ^
drivers/hwtracing/coresight/coresight-tpdm.h:208:3: note: expanded from macro 'CMB_PATT_ENABLE_TS'
  208 |                 tpdm_patt_enable_ts(enable_ts,                  \
      |                 ^
drivers/hwtracing/coresight/coresight-tpdm.h:156:5: note: expanded from macro 'tpdm_patt_enable_ts'
  156 |            }                                                    \
      |            ^

Make sure we initialise this.

Fixes: dc6ce57e ("coresight-tpdm: Add timestamp control register support for the CMB")
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Cc: Tao Zhang <quic_taozha@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>

drivers/hwtracing/coresight/coresight-tpdm.h

@@ -153,6 +153,7 @@
 		__ATTR(name, 0644, enable_ts_show,		\
 		enable_ts_store),		\
 		mem,						\
+		0,						\
 	   }							\
 	})[0].attr.attr)