staging: rtl8192e: rtl8192e: Correct misspelt variable name

Correct misspelt variable name.
Misspelling found using checkpatch.pl.

Signed-off-by: R Veera Kumar <vkor@vkten.in>
Link: https://lore.kernel.org/r/20200405174247.7868-1-vkor@vkten.in


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>