mesa: rename format_(un)pack.c functions to match format names (pt. 5)

mesa: rename format_(un)pack.c functions to match format names (pt. 5)

sed commands:
s/SIGNED_R_UNORM8\b/R_SNORM8/g
s/SIGNED_RG88_REV\b/R8G8_SNORM/g
s/SIGNED_RGBX8888\b/X8B8G8R8_SNORM/g
s/SIGNED_A8B8G8R8_UNORM\b/A8B8G8R8_SNORM/g
s/SIGNED_R8G8B8A8_UNORM\b/R8G8B8A8_SNORM/g
s/SIGNED_R_UNORM16\b/R_SNORM16/g
s/SIGNED_R16G16_UNORM\b/R16G16_SNORM/g
s/SIGNED_RGB_16\b/RGB_SNORM16/g
s/SIGNED_RGBA_16\b/RGBA_SNORM16/g
s/SIGNED_A_UNORM8\b/A_SNORM8/g
s/SIGNED_L_UNORM8\b/L_SNORM8/g
s/SIGNED_L8A8_UNORM\b/L8A8_SNORM/g
s/SIGNED_L_UNORM8\b/I_SNORM8/g
s/SIGNED_A_UNORM16\b/A_SNORM16/g
s/SIGNED_L_UNORM16\b/L_SNORM16/g
s/SIGNED_L16A16_UNORM\b/LA_SNORM16/g
s/SIGNED_L_UNORM16\b/I_SNORM16/g
s/XBGR16161616_SNORM\b/RGBX_SNORM16/g
s/SIGNED_G8R8_UNORM\b/G8R8_SNORM/g
s/SIGNED_G16R16_UNORM\b/G16R16_SNORM/g
s/SIGNED_I_UNORM8\b/I_SNORM8/g
s/SIGNED_I_UNORM16\b/I_SNORM16/g

Reviewed-by: Reviewed-by: Roland Scheidegger <sroland@vmware.com>