sparc: defconfig: Cleanup from old Kconfig options

Remove old, dead Kconfig options (in order appearing in this commit):
 - EXPERIMENTAL is gone since v3.9;
 - INET_LRO: commit 7bbf3cae ("ipv4: Remove inet_lro library");
 - AUTOFS_FS: commit 561c5cf9 ("staging: Remove autofs3");
 - RCU_CPU_STALL_DETECTOR: commit a00e0d71 ("rcu: Remove conditional
   compilation for RCU CPU stall warnings");
 - USB_DEVICE_CLASS: commit 007bab91 ("USB: remove
   CONFIG_USB_DEVICE_CLASS");
 - SYSCTL_SYSCALL_CHECK: commit 7c60c48f ("sysctl: Improve the
   sysctl sanity checks");

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>