staging: gpib: Fix inadvertent negative shift

During the initial checkpatch cleanup, when removing blanks
after open parentheses, a minus sign in the argument of a shift
operation was deleted by mistake. This transformed a pre-decrement
operation into a negation.

The result of a negative shift is undefined and a warning was
signalled by sparse.

Restore the pre-decrement operation.

Fixes: 6c52d5e3cde2 ("staging: gpib: Add common include files for GPIB drivers")
Signed-off-by: Dave Penkler <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/gpib/include/amcc5920.h

···
 
 static inline uint32_t amcc_wait_state_bits(unsigned int region, unsigned int num_wait_states)
 {
-	return (num_wait_states & 0x7) << (-region * bits_per_region);
+	return (num_wait_states & 0x7) << (--region * bits_per_region);
 };
 
 enum amcc_prefetch_bits {