riscv: DONT_TRANSLATE modifies_sip

To prevent a contradiction, the C parser does not allow a function to
claim both what it modifies and possess a body that may modify something
else. Instruct the C parser to not translate it in order for the
MODIFIES clause to take precedence.

Signed-off-by: Rafal Kolanski <rafal.kolanski@data61.csiro.au>

include/arch/riscv/arch/machine.h

@@ -153,6 +153,7 @@ static inline word_t read_sstatus(void)
 }
 
 /** MODIFIES: */
+/** DONT_TRANSLATE */
 static inline word_t read_sip(void)
 {
     word_t temp;