lcd: rename bitmap_plot to better represent its functionality

lcd: rename bitmap_plot to better represent its functionality

The name "bitmap_plot" is misleading because it implies that this is a generic
function capable of dealing with any bitmap, but its implementation only works
with the logo data.

Rename the function to better reflect this.

Signed-off-by: Nikita Kiryanov <[email protected]>
Reviewed-by: Simon Glass <[email protected]>
Tested-by: Bo Shen <[email protected]>
Tested-by: Josh Wu <[email protected]>
Cc: Simon Glass <[email protected]>
Cc: Anatolij Gustschin <[email protected]>