memtester: Corrected recipe following review comments and guidelines

This is an import of memtester from OE classic,
commit ID: 5671855bfba71575e4919c4b5fc9c5dcb8052612

Fixes to recipe:
* Added patch header to Makefile.patch
* Corrected order of variables and added HOMEPAGE to recipe
* Removed the line, S = "${WORKDIR}/memtester-${PV}" as its the default
* Removed new-line at end of recipe

Signed-off-by: Joel A Fernandes <joelagnel@ti.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>