lib/vdso: Remove checks on return value for 32 bit vDSO

Since all the architectures that support the generic vDSO library have
been converted to support the 32 bit fallbacks it is not required
anymore to check the return value of __cvdso_clock_get*time32_common()
before updating the old_timespec fields.

Remove the related checks from the generic vdso library.

References: c60a32ea ("lib/vdso/32: Provide legacy syscall fallbacks")
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20190830135902.20861-6-vincenzo.frascino@arm.com