compat: remove backport of irq_modify_status

compat: remove backport of irq_modify_status

Only kernel >= 2.6.39 irq_to_desc or irq_desc are exporting, so that
compat is not able to access this on the kernel versions where it is
needed. irq_to_desc and irq_desc are defined in the header files so
compilation works, but the module is not loadable because of the
missing exported symbol which make compat unusable on all these kernel
versions. Remove this function, no driver seams to need it.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Luis R. Rodriguez <mcgrof@frijolero.org>