rtc: ds3232: fix WARNING trace in resume function

If ds3232 work on some platform that is not implementing
irq_set_wake, ds3232 will get a WARNING trace in resume.
So fix ds3232->suspended state to false when irq_set_irq_wake
return error.

WARNING: CPU: 0 PID: 729 at kernel/irq/manage.c:604 irq_set_irq_wake+0x4b/0x8c()
Unbalanced IRQ 201 wake disable
Modules linked in:
CPU: 0 PID: 729 Comm: sh Not tainted 3.12.19-rt30+ #25
[<800107d9>] (unwind_backtrace+0x1/0x88) from [<8000e4ef>] (show_stack+0xb/0xc)
[<8000e4ef>] (show_stack+0xb/0xc) from [<802b5fa9>] (dump_stack+0x4d/0x60)
[<802b5fa9>] (dump_stack+0x4d/0x60) from [<800186dd>] (warn_slowpath_common+0x45/0x64)
[<800186dd>] (warn_slowpath_common+0x45/0x64) from [<80018717>] (warn_slowpath_fmt+0x1b/0x24)
[<80018717>] (warn_slowpath_fmt+0x1b/0x24) from [<8003a8d3>] (irq_set_irq_wake+0x4b/0x8c)
[<8003a8d3>] (irq_set_irq_wake+0x4b/0x8c) from [<80204fcb>] (ds3232_resume+0x2d/0x36)
[<80204fcb>] (ds3232_resume+0x2d/0x36) from [<801954c7>] (dpm_run_callback.isra....