sunxi:g2d Rename sun4i_g2d --> sunxi_g2d

Rename drivers/char/sun4i_g2d directory drivers/char/sunxi_g2d
Change all file/directory references from sun4i_g2d to sunxi_g2d
Change all config references from CONFIG_SUN4I_G2D to CONFIG_SUNXI_G2D
Change arch/arm/plat-sunxi/core.c to use IS_ENABLED(CONFIG_SUNXI_G2D)
  instead of defined CONFIG_SUN4I_G2D || defined CONFIG_SUN4I_G2D_MODULE
sunxi:g2d Change from hard-coded interrupt to SW_INT_IRQNO_MP
sunxi:g2d Enable G2D for SUN7I