block: bfq: Squashed update from BFQ-v7r4 to BFQ-v7r5

Change-Id: I749ef141246db7020cec0b10d980ec854a572603
build-script: Add compilation duration info
Signed-off-by: shivamk11 <shivamk11@gmail.com>
linux: mm: set readahead 256 kb