tpacpi-bat: E420s/S420 $aslBase change

[xlz]

For ThinkPad Edge E420s and S420 (mine, ~=E420s), $aslBase should be changed to \_SB.PCI0.LPCB.EC0.HKEY.

Launchpad has collected quite some DSDT here. I did a quick check for LPC.EC.HKEY code:

• T400, T410, T500, T510, and W500 have no such code;
• E420s (S420), E520, T420, T420s, T520, W520 have the same code for LPC.EC.HKEY or LPCB.EC0.HKEY.

[teleshoes]

i should probably do a detect instead of just changing it; i get the impression that this is deprecated and for backwards compatibility only. ill look into it.

also, thanks!