meminfo: Fix ProcMemInfo ForEachVmaFromFile

Caused by passing invalid parameters to getline(3) and the test
failure went unnoticed.

Bug: 111694435
Test: libmeminfo_test 1 --gtest_filter=TestProcMemInfo.ForEachVmaFromFileTest
Change-Id: Ideb39604c58f89237b05d2f7c8edb67c5ae65768
Merged-In: Ideb39604c58f89237b05d2f7c8edb67c5ae65768
Signed-off-by: Sandeep Patil <sspatil@google.com>