V4L/DVB (5001): Add two required headers on kernel 2.6.20-rc1

V4L/DVB (5001): Add two required headers on kernel 2.6.20-rc1

include/media/ir-common.h:78: error: field 'work' has incomplete type
drivers/media/common/ir-functions.c: In function 'ir_rc5_timer_end':
drivers/media/common/ir-functions.c:301: error: 'jiffies' undeclared (first use in this function)
drivers/media/common/ir-functions.c:301: error: (Each undeclared identifier is reported only once)
drivers/media/common/ir-functions.c:301: error: for each function it appears in.)
drivers/media/common/ir-functions.c:347: error: 'HZ' undeclared (first use in this function)

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>