w83977af_ir: remove two faux Kconfig macros

Ever since v2.3.5 the driver for "Winbond W83977AF (IR)" contains two
unneeded preprocessor macros.

CONFIG_NETWINDER_TX_DMA_PROBLEMS is never defined and can safely be
removed. And CONFIG_NETWINDER_RX_DMA_PROBLEMS is just an alias for
CONFIG_ARCH_NETWINDER, so that (valid) Kconfig macro can be used
instead.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: David S. Miller <davem@davemloft.net>