RFC: ANDROID: net: ipv4: sysfs_net_ipv4: Fix TCP window size controlling knobs

Refactor /sys/kernel/ipv4/tcp_* send/receive window size controlling
knobs to align with the changes of upstream commit 356d1833
("tcp: Namespace-ify sysctl_tcp_rmem and sysctl_tcp_wmem").

Fixes: ("ANDROID: net: ipv4: sysfs_net_ipv4: Add sysfs-based knobs for controlling TCP window size")
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>