coresight: include vmalloc.h for vmap/vunmap

coresight: include vmalloc.h for vmap/vunmap

The newly introduced code fails to build in some configurations
unless we include the right headers:

drivers/hwtracing/coresight/coresight-tmc-etr.c: In function 'tmc_free_table_pages':
drivers/hwtracing/coresight/coresight-tmc-etr.c:206:3: error: implicit declaration of function 'vunmap'; did you mean 'iounmap'? [-Werror=implicit-function-declaration]

Fixes: 79613ae8715a ("coresight: Add generic TMC sg table framework")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>