tests: Fix gcov typo for tmp105-test

Commit 6e998903 introduced a new qtest
test case but misspelled gcov, leading to no coverage analysis. Fix it.
Signed-off-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

tests/Makefile

@@ -61,7 +61,7 @@ check-qtest-sparc-y = tests/m48t59-test$(EXESUF)
 check-qtest-sparc64-y = tests/m48t59-test$(EXESUF)
 gcov-files-sparc-y += hw/m48t59.c
 check-qtest-arm-y = tests/tmp105-test$(EXESUF)
-qcov-files-arm-y += hw/tmp105.c
+gcov-files-arm-y += hw/tmp105.c
 
 GENERATED_HEADERS += tests/test-qapi-types.h tests/test-qapi-visit.h tests/test-qmp-commands.h