include sys/types.h for uint definition

uint is defined in sys/types.h, therefore this
header needs to be included, it gets exposed with
musl where this header is not getting included indirectly
as it is happening when building on glibc

Fixes build errors on musl e.g.
upm/src/kx122/kx122.hpp:456:31: error: 'uint' has not been declared
|        void setBufferThreshold(uint samples);
|                                ^~~~

Signed-off-by: Khem Raj <raj.khem@gmail.com>

src/kx122/kx122.h

@@ -31,6 +31,7 @@ extern "C"{
 #include <assert.h>
 #include <unistd.h>
 #include <math.h>
+#include <sys/types.h>
 
 #include <mraa/i2c.h>
 #include <mraa/spi.h>