fbcon: Fix error paths in set_con2fb_map

This is a regressoin introduced in b07db395 ("fbcon: Ditch error
handling for con2fb_release_oldinfo"). I failed to realize what the if
(!err) checks. The mentioned commit was dropping the
con2fb_release_oldinfo() return value but the if (!err) was also
checking whether the con2fb_acquire_newinfo() function call above
failed or not.

Fix this with an early return statement.

Note that there's still a difference compared to the orginal state of
the code, the below lines are now also skipped on error:

	if (!search_fb_in_map(info_idx))
		info_idx = newidx;

These are only needed when we've actually thrown out an old fb_info
from the console mappings, which only happens later on.

Also move the fbcon_add_cursor_work() call into the same if block,
it's all protected by console_lock so doesn't matter when we set up
the blinking cursor delayed work anyway. This further simplifies the
control flow and allows us to ditch the found local variable.

v2: Clarify commit message (Javier)

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Helge Deller <deller@gmx.de>
Tested-by: Xingyuan Mo <hdthky0@gmail.com>
Fixes: b07db395 ("fbcon: Ditch error handling for con2fb_release_oldinfo")
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Xingyuan Mo <hdthky0@gmail.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v5.19+