EDAC: i5100_edac: get rid of an unused var

As reported by GCC with W=1:

	drivers/edac/i5100_edac.c:714:16: warning: variable ‘et’ set but not used [-Wunused-but-set-variable]
	  714 |  unsigned long et;
	      |                ^~

It sounds some left over from some code before the addition of
an udelay().

Acked-by: Borislav Petkov <bp@alien8.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>