lib/fonts: Fix bit position when rotating by 180 degrees

Fix the horizontal bit position when rotating a glyph by 180°. The
original code in rotate_ud() rounded the value in width up to a
multiple of 8, aka the bit pitch, and calculated the rotated pixel
from that value. The new code stores the glyph's pitch in bit_pitch,
but fails to update the rotated pixel's output accordingly. Simply
replacing the variable does this.

The bug can be reproduced by setting a font with an unaligned width,
such as sun12x22, like this:

 setfont sun12x22
 echo 2 > /sys/class/graphics/fbcon/rotate

Without the fix, the font looks distorted.

Fixes: a30e9e6b018f ("lib/fonts: Refactor glyph-rotation helpers")
Closes: https://lore.gitlab.freedesktop.org/drm-ai-reviews/review-patch7-20260407092555.58816-8-tzimmermann@suse.de/
Cc: dri-devel@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>