am335x: cpsw: optimize cpsw_recv to increase network performance

In 48ec5291, only TX path was optimized; this does the same also for RX
path. This results in huge increase of TFTP throughput on custom am3352
board (from 312KiB/s to 1.8MiB/s) and eliminates occasional transfer
timeouts.

Signed-off-by: Vladimir Koutny <vladimir.koutny@streamunlimited.com>
Cc: Mugunthan V N <mugunthanvnm@ti.com>
Cc: Joe Hershberger <joe.hershberger@gmail.com>
Cc: Tom Rini <trini@ti.com>
ti_armv7_common.h: enable btrfs support

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
Introduced btrfs file-system with btrload command

Introduces btrfs file-system to read file from
volume/sub-volumes with btrload command. This
implementation has read-only support.
This btrfs implementation is based on syslinux btrfs
code.

v14:     Merge conflicts, makefile updates and do_load API changes
v13:     Added pre-calculated crc for BE & LE
v11:     Mirro super block check.
v10:     patch problem reworked.
v5:      merged with master.
v4:      btrls command added.

[port of syslinux commit 269ebc845ebc8b46ef4b0be7fa0005c7fdb95b8d]

Signed-off-by: Adnan Ali <adnan.ali@codethink.co.uk>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>