Resolution choices under Settings | View Scaling menu are not correct

[dtremblay]

The resolution choices shown are 640x480 and 640x400. The 640x400 resolution only applies to the F256.
The resolution should obey the Master Control Register (MCR). For FMX, the resolution of 800x600 should be available, only when the H bit is set.

A table should be build, based on the different boards, e.g.

            |   Rev B   |   Rev C |  Rev U | Rev U+ | Rev F256Jr |  Rev F256Jr (816) | Rev F256K | Rev F256K (816) |  
640x480     |    X      |     X   |    X   |     X  |     X      |        X          |    X      |       X         | 
640x400     |           |         |        |        |     X      |        X          |    X      |       X         | 
800x600     |           |     X   |        |        |            |                   |           |                 | 

We need to confirm what the actual modes are.