ANDROID: docs: sysctl: vm: Fix merge error relating to extra_free_kbytes

This hunk should not have been retained.

This re-aligns with Mainline.

Fixes: 3cc02cd189 ("Revert "ANDROID: add extra free kbytes tunable"")
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Change-Id: I04ad519f03784fed1ad2f9ff3fa4fff2bc9ea5de

Documentation/admin-guide/sysctl/vm.rst

@@ -37,7 +37,6 @@ Currently, these files are in /proc/sys/vm:
 - dirty_writeback_centisecs
 - drop_caches
 - extfrag_threshold
-- extra_free_kbytes
 - highmem_is_dirtyable
 - hugetlb_shm_group
 - laptop_mode
@@ -300,21 +299,6 @@ only use the low memory and they can fill it up with dirty data without
 any throttling.
 
 
-extra_free_kbytes
-
-This parameter tells the VM to keep extra free memory between the threshold
-where background reclaim (kswapd) kicks in, and the threshold where direct
-reclaim (by allocating processes) kicks in.
-
-This is useful for workloads that require low latency memory allocations
-and have a bounded burstiness in memory allocations, for example a
-realtime application that receives and transmits network traffic
-(causing in-kernel memory allocations) with a maximum total message burst
-size of 200MB may need 200MB of extra free memory to avoid direct reclaim
-related latencies.
-
-==============================================================
-
 hugetlb_shm_group
 =================