oeqa/parselogs: grep for exact errors list keywords

Given grep expression looks for error strings regardless of the
semantics and this ends up it flagging things like

***********************
Log: /mnt/a/yoe/build/tmp/work/raspberrypi3_64-yoe-linux-musl/yoe-qt5-wayland-image/1.0-r0/target_logs/weston.log
-----------------------
Central error:                EGL_KHR_create_context_no_error EGL_KHR_fence_sync
***********************

here EGL_KHR_create_context_no_error is an API, therefore the check
should be tightened a bit so explicitly look for error words so such
false positives don't show up

This helps in fixing wrong matches e.g. on rpi3 dmesg have strings like
above

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>