ext2: Cache line aligned partial sector bounce buffer

ext2: Cache line aligned partial sector bounce buffer

Currently, if a device read request is done that does not begin or end
on a sector boundary a stack allocated bounce buffer is used to perform
the read, and then just the part of the sector that is needed is copied
into the users buffer.  This stack allocation can mean that the bounce
buffer will not be aligned to the dcache line size.  This is a problem
when caches are enabled because unaligned cache invalidates are not
safe.

This patch uses ALLOC_CACHE_ALIGN_BUFFER to create a stack allocated
cache line size aligned bounce buffer.

Signed-off-by: Anton Staaf <robotboy@chromium.org>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Dave Liu <r63238@freescale.com>
Cc: Andy Fleming <afleming@gmail.com>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Change-Id: I32e1594d90ef039137bb219b0f7ced55768744ff
Acked-by: Mike Frysinger <vapier@gentoo.org>