psplash: update to latest git version

Latest git version contains various changes, including
fix for big endian RGB888 rendering. It also makes the patch:
"0001-psplash-fb-Convert-psplash_fb_plot_pixel-to-a-static.patch"
unnecessary, as this patch has been upstreamed.

[YOCTO#7236]

Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>