drm/i915/sysfs: convert snprintf to sysfs_emit

Fix the following coccicheck warning:
drivers/gpu/drm/i915//i915_sysfs.c:266:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:285:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:276:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:335:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:390:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:465:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:107:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:75:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:83:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:91:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:99:8-16:
WARNING: use scnprintf or sprintf
drivers/gpu/drm/i915//i915_sysfs.c:326:8-16:
WARNING: use scnprintf or sprintf

Signed-off-by: Xuezhi Zhang <zhangxuezhi1@yulong.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210404084103.528211-1-llyz108@163.com