V4L/DVB: irmon: Cleanup some warning noise

Driver is not properly initializing u64 constants on 32 bit systems:
drivers/media/IR/imon.c:301: warning: integer constant is too large for ‘long’ type
drivers/media/IR/imon.c:302: warning: integer constant is too large for ‘long’ type
drivers/media/IR/imon.c:304: warning: integer constant is too large for ‘long’ type
drivers/media/IR/imon.c:305: warning: integer constant is too large for ‘long’ type
drivers/media/IR/imon.c:308: warning: integer constant is too large for ‘long’ type
drivers/media/IR/imon.c:309: warning: integer constant is too large for ‘long’ type
drivers/media/IR/imon.c:310: warning: integer constant is too large for ‘long’ type

Fix also a few troubles at error printk handling:
drivers/media/IR/imon.c: In function ‘imon_init_intf0’:
drivers/media/IR/imon.c:1909: warning: ‘ret’ may be used uninitialized in this function
drivers/media/IR/imon.c: In function ‘imon_init_intf1’:
drivers/media/IR/imon.c:1989: warning: ‘ret’ may be used uninitialized in this function

Cc: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>