MIPS: BMIPS: Adjust mips-hpt-frequency for BCM7435

The CPU actually runs at 1405Mhz which gives us a 175625000 Hz MIPS timer
frequency (CPU frequency / 8).

Fixes: e4c7d009

 ("MIPS: BMIPS: Add BCM7435 dtsi")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: john@phrozen.org
Cc: cernekee@gmail.com
Cc: jaedon.shin@gmail.com
Patchwork: https://patchwork.linux-mips.org/patch/13132/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>