drm/i915: remove parens around revision ids

#define IS_PRELIMINARY_HW(intel_info) ((intel_info)->is_preliminary)

#define SKL_REVID_A0		(0x0)

#define SKL_REVID_B0		(0x1)

#define SKL_REVID_C0		(0x2)

#define SKL_REVID_D0		(0x3)

#define SKL_REVID_E0		(0x4)

#define SKL_REVID_F0		(0x5)

#define BXT_REVID_A0		(0x0)

#define BXT_REVID_B0		(0x3)

#define BXT_REVID_C0		(0x9)

#define SKL_REVID_A0		0x0

#define SKL_REVID_B0		0x1

#define SKL_REVID_C0		0x2

#define SKL_REVID_D0		0x3

#define SKL_REVID_E0		0x4

#define SKL_REVID_F0		0x5

#define BXT_REVID_A0		0x0

#define BXT_REVID_B0		0x3

#define BXT_REVID_C0		0x9

/*

 * The genX designation typically refers to the render engine, so render