V4L2EncodeComponent: fix build error

Patch 0fa30254bd7e introduced a type mismatch when building for 32-bit architecture. This error is visible when running "mmm external/v4l2_codec2":

    external/v4l2_codec2/components/V4L2EncodeComponent.cpp:782:32: error: no matching function for call to 'max'
            int64_t newFramerate = std::max(
                                   ^~~~~~~~
    external/libcxx/include/algorithm:2529:1: note: candidate template ignored: deduced conflicting types for parameter '_Tp' ('long' vs. 'long long')
    max(const _Tp& __a, const _Tp& __b)
    ^
    external/libcxx/include/algorithm:2539:1: note: candidate template ignored: could not match 'initializer_list<type-parameter-0-0>' against 'long'
    max(initializer_list<_Tp> __t, _Compare __comp)
    ^
    external/libcxx/include/algorithm:2547:1: note: candidate function template not viable: requires single argument '__t', but 2 arguments were provided
    max(initializer_list<_Tp> __t)
    ^
    external/libcxx/include/algorithm:2521:1: note: candidate function template not viable: requires 3 arguments, but 2 were provided
    max(const _Tp& __a, const _Tp& __b, _Compare __comp)
    ^

Fix this by casting the right member of the cmp operation to int64_t.

Test: mmm external/v4l2_codec2

Change-Id: Id2cc220b9122eec412823f577f07ecd82bad60fc
(cherry picked from commit a0377993b84da09547aad11f2f27560e0bf4dcd5)