Option: uae_cpuboardmem1_size

For the following accelerator boards, setting this option is the same as
specifying [uae_mbresmem_size] (FIXME: see below):

* Blizzard 2060
* CyberStorm MK 1
* CyberStorm MK II
* CyberStorm MK III
* CyberStorm PPC
* Warp Engine
* Tek Magic

FIXME: check effect on "cyberstorm" bank with CyberStorm MK III and 
       CyberStorm PPC