target/disassembler: update capstone include path to <capstone.h>

on macos (homebrew base) `pkg-config --cflags capstone` output with
`-I/opt/homebrew/Cellar/capstone/4.0.2/include/capstone`
gcc not find headers on parent "include" path,
causes build error `fatal error: 'capstone/capstone.h' file not found`
it's ok to change to <capstone.h> for all platforms.

Signed-off-by: fatalc <cnfatal@gmail.com>
Change-Id: Ia2e2058024d4fc1a57a8b4ea847c664d74f67efb
Reviewed-on: https://review.openocd.org/c/openocd/+/6946


Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>