Fix an error definition about the variable 'fname'

The variable 'fname' is mistakenly defined two twice, the first definition
is in the vmcore-dmesg.c, and the second definition is in the elf_info.c.
That is confused and incorrect although it's a static type, because the
value of variable 'fname' is not assigned(set) in elf_info.c. Anyway, its
value will be always 'null' when printing an error information.

Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
Signed-off-by: Simon Horman <horms@verge.net.au>