staging: sm750fb: Fix typo frambuffer->framebuffer

This patch corrects a typo (frambuffer->framebuffer) in the
sm750fb_fram(e)buffer_release and sm750fb_fram(e)buffer_alloc function
names.

Signed-off-by: Aymen Qader <qader.aymen@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>