brcmsmac: remove some redundant chip common workarounds

The removed workarounds are already performed in bcma_pmu_workarounds()
and bcma_core_chipcommon_init()

This patch depends on the completion of the workarounds in bcma done in
this commit in my pending patch series for bcma.
Author: Hauke Mehrtens <hauke@hauke-m.de>
Date:   Mon Jun 4 00:20:26 2012 +0200

    bcma: complete workaround for BCMA43224 and BCM4313

Acked-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>