fbdev: Remove FBINFO_FLAG_DEFAULT from framebuffer_alloc()'ed structs

The flag FBINFO_FLAG_DEFAULT is 0 and has no effect, as struct
fbinfo.flags has been allocated to zero by framebuffer_alloc(). So
do not set it.

Flags should signal differences from the default values. After cleaning
up all occurrences of FBINFO_DEFAULT, the token will be removed.

v4:
	* clarify commit message (Geert, Dan)
v2:
	* fix commit message (Miguel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Jaya Kumar <jayalk@intworks.biz>
Cc: Helge Deller <deller@gmx.de>
Cc: Peter Jones <pjones@redhat.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Maik Broemme <mbroemme@libmpq.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Cc: Teddy Wang <teddy.wang@siliconmotion.com>
Cc: Michal Januszewski <spock@gentoo.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230715185343.7193-15-tzimmermann@suse.de