dasharo/bootsplash.bmp; Fix logo rotation and background

The Dasharo logo was slightly rotated. The sharp point of the shield
was not going through the center of the cross in a straight line.

Also make the background really black (000000 hex). previously it was
000200 hex.

Signed-off-by: Michał Żygowski <michal.zygowski@3mdeb.com>