media: pvrusb2: fix the retry logic

media: pvrusb2: fix the retry logic

As reported by this warning:
	drivers/media/usb/pvrusb2/pvrusb2-encoder.c:263 pvr2_encoder_cmd() warn: continue to end of do { ... } while(0); loop

There's an issue at the retry logic there: the current logic is:

	do {
		if (need_to_retry)
			continue;

		some_code();
	} while (0);

Well, that won't work, as continue will make it test for zero, and
abort the loop. So, change the loop to:

	while (1) {
		if (need_to_retry)
			continue;

		some_code();
		break;
	};

With seems to be what's actually expected there.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>