ProcDiskstatsTest: support 4.19 kernel

The format of /proc/diskstats changed in 4.19. Update the VTS test
accordingly.

Bug: 121379490
Test: run vts-kernel -m VtsKernelProcFileApi
Change-Id: I9f62c8174f3e184072771466835077afef1a051f
diff --git a/api/proc/ProcFsFileTests.py b/api/proc/ProcFsFileTests.py
index 266e781..0dc3f40 100644
--- a/api/proc/ProcFsFileTests.py
+++ b/api/proc/ProcFsFileTests.py
@@ -28,7 +28,8 @@
     p_lines = repeat_rule('line')
 
     def p_line(self, p):
-        '''line : NUMBER NUMBER STRING NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NEWLINE'''
+        '''line : NUMBER NUMBER STRING NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NEWLINE
+                | NUMBER NUMBER STRING NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NUMBER NEWLINE'''
         p[0] = p[1:]
 
     def get_path(self):