bcma: delete duplicate readl

The 'val' has already been read by the prior call to 'mips_busprobe32';
this 'readl' is unnecessary.

Signed-off-by: Nathan Hintz <nlhintz@hotmail.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>