m68k: mvme147,mvme16x: Don't wipe PCC timer config bits

In the Linux kernel, the following vulnerability has been resolved: m68k: mvme147,mvme16x: Don't wipe PCC timer config bits Don't clear the timer 1 configuration bits when clearing the interrupt flag and counter overflow. As Michael reported, "This results in no timer interrupts being delivered after the first. Initialization then hangs in calibrate_delay as the jiffies counter is not updated." On mvme16x, enable the timer after requesting the irq, consistent with mvme147.