coresight-tmc: Fix false positive -Wfortify-source

The size is checked just above.

../drivers/hwtracing/coresight/coresight-tmc.c:423:26: warning: 'sscanf' may overflow; destination buffer in argument 3 has size 10, but the corresponding specifier may require size 11 [-Wfortify-source]
  423 |         if (sscanf(buf, "%10s", str) != 1)
      |                                 ^
../drivers/hwtracing/coresight/coresight-tmc.c:464:26: warning: 'sscanf' may overflow; destination buffer in argument 3 has size 10, but the corresponding specifier may require size 11 [-Wfortify-source]
  464 |         if (sscanf(buf, "%10s", str) != 1)
      |                                 ^
2 warnings generated.

Change-Id: I5db199a85ba0c7dfc15fae5d62c9c4d8c550d3e7
Signed-off-by: Alexander Winkowski <dereference23@outlook.com>